NCERT Solutions Class 5 Mathematics Mela Chapter 12 Racing Seconds

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Question 1. At what time did Raghav start practising Yoga?
Answer: Raghav began his yoga session at 5:35 A.M.
In simple words: Raghav started doing yoga at 5:35 in the morning.

Exam Tip: When reading a clock, identify the hour hand position first, then note the minute hand to get the exact time.

Question 2. At what time did he finish?
Answer: Raghav completed his yoga practice at 5:55 A.M.
In simple words: He finished doing yoga at 5:55 in the morning.

Exam Tip: Pay close attention to the exact position of clock hands to avoid reading the time incorrectly.

Question 3. How much time did he spend practising Yoga?
Answer: Yoga start time = 5:35 A.M. Yoga finish time = 5:55 A.M. Time spent on practising yoga = 5:55 A.M. - 5:35 A.M. = 20 minutes
In simple words: Raghav spent 20 minutes doing yoga, from when he started until he finished.

Exam Tip: To find elapsed time, subtract the start time from the finish time, working through minutes and hours separately if needed.

Question 4. Find the time elapsed between the given time periods. Share your strategies.
(a) 01:15 p.m. to 01:42 p.m.?
(b) 03:18 p.m. to 08:18 p.m.?
(c) 09:15 a.m. to 11:30 a.m.?
Answer:
(a) Start Time = 1:15 p.m. End time = 1:42 p.m. Elapsed time = End time - Start time = 1:42 - 1:15 = 27 minutes
(b) Start Time = 3:18 p.m. End time = 8:18 p.m. Elapsed time = End time - Start time = 8:18 - 3:18 = 5 hours
(c) Start Time = 9:15 a.m. End time = 11:30 p.m. Elapsed time = End time - Start time = 11:30 - 9:15 = 2 hours 15 minutes
In simple words: To find how much time passed, take the end time and subtract the start time. If only minutes change, just subtract the minutes. If hours change too, subtract hours and minutes separately.

Exam Tip: When both hours and minutes are involved, handle them independently - subtract hours from hours and minutes from minutes.

Question 5. The table below shows the time taken by 3 children to paint a picture.
Answer:

In simple words: Looking at the table, we can see how long each child took to finish painting. Raghav was the fastest, Ritu took longer, and Rani took the longest time.

Exam Tip: When comparing times shown in a table, convert them all to the same unit (all minutes or all hours and minutes) to make comparison easier.

Question 5(a). Who took the longest time?
Answer: Rani took the longest time of 2 hours 10 minutes.
In simple words: Rani spent more time painting than the other two children.

Exam Tip: To find who took the longest time, look at each duration and pick the biggest number.

Question 5(b). Who took the least time?
Answer: Raghav took the least time of 1 hour 20 minutes.
In simple words: Raghav finished his painting faster than Rani and Ritu.

Exam Tip: To find who took the least time, compare all the durations and pick the smallest one.

Question 6. Fill in the blanks by writing the time in the appropriate format.
Answer:

In simple words: In the 12-hour format, we use a.m. for morning and p.m. for afternoon or evening. In the 24-hour format, morning times stay the same, but afternoon and evening times have 12 added to them.

Exam Tip: For p.m. times, add 12 to the hour to convert to 24-hour format (except 12:00 p.m. which stays as 12:00). For a.m. times, the hours usually stay the same (except 12:00 a.m. which becomes 00:00).

Question 7. Match the following.
Answer:

In simple words: Each time written in the 12-hour way matches with the same time written in the 24-hour way. Match them by checking if the hours and minutes are the same, and remember that p.m. times get 12 added to them.

Exam Tip: When matching time formats, check the minutes first - they never change. Then check the hours, remembering the conversion rule for a.m. and p.m. times.

School Race

In situations like a race, seconds help us see small differences in the time taken by participants. Each participant took 1 minute but how much more?

Question. Who took the longest time?
Answer: First place took 55 seconds more than 1 minute. Second place took 56 seconds more than 1 minute. Third place took 57 seconds more than 1 minute.
In simple words: The three runners each took a little more than 1 minute. The first-place runner was fastest, and the third-place runner was slowest.

Exam Tip: When times are very close together, seconds become important for telling who was fastest. Reading seconds carefully is the key to accurate timekeeping in races.

Question. Identify the child who won the race. How much time did the child take?
Answer: Winner: The child in the red shirt won the race, standing at the number 1 position on the victory podium. Time Taken: The winning child took 1 minute and 55 seconds to complete the race.
In simple words: The child wearing red was the fastest. That child finished in 1 minute and 55 seconds.

Exam Tip: In a race, the person with the smallest total time wins. Always read the podium positions carefully - first place is the winner.

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Let Us Do

Estimate whether you would take seconds or minutes to complete the following activities. Tick the appropriate cell.

Question. Estimate whether you would take seconds or minutes to complete the following activities. Tick the appropriate cell.
Answer:

In simple words: Quick, instant actions like blinking or switching lights take seconds. Longer activities like melting ice or washing hands take minutes.

Exam Tip: Think about how quickly you can do each activity - if it happens in a flash, it takes seconds; if it takes a while, it takes minutes.

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List events other than the ones listed above that you can do or that can happen in less than a minute or in a few seconds.

Question. List events other than the ones listed above that you can do or that can happen in less than a minute or in a few seconds.
Answer: Tying shoelaces - minutes. Brushing your teeth - minutes. Opening a door - seconds. Turning on a fan - seconds. Clapping your hands - seconds. Chewing a bite of food - minutes.
In simple words: Some activities are quick (take seconds), while others need more time (take minutes). Tying shoelaces and brushing teeth take a few minutes, but opening a door or clapping happens in seconds.

Exam Tip: When listing activities, think realistically about how long each one actually takes. If you've done it before, remember how long it felt.

Question. Estimate and verify how many of these you can do in a minute.
Answer:

In simple words: We guessed how many times we could do each activity in 1 minute, then we actually tried it and counted the real number. Sometimes we guessed right, sometimes we guessed higher or lower.

Exam Tip: When comparing estimated and actual numbers, note how close your guess was. This helps you improve your ability to estimate time and quantities in the future.

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Let Us Find

Question 1. Find out the number of times you can skip the rope in 10 seconds.
Answer: I am good at skipping. I can do around 8 - 10 skips in 10 seconds.
In simple words: In 10 seconds, I can jump rope about 8 to 10 times.

Exam Tip: When doing a physical activity like rope skipping, try it a few times to get an accurate count rather than just guessing.

Question 2. How long does it take you to write the word FRIEND?
Answer: It takes 3 seconds if I write fast.
In simple words: When I write the word FRIEND quickly, it takes about 3 seconds.

Exam Tip: When timing yourself doing something, write at your normal pace the first time, then try once more to see how fast you can really do it.

Question 3. How long does it take you to run 100 m?
Answer: I take about 20 seconds, but when I tried to run, it takes 18 seconds only.
In simple words: I thought running 100 metres would take me 20 seconds, but when I actually ran it, I did it in 18 seconds.

Exam Tip: Your actual time might differ from your estimate. Keep track of both to see how good you are at judging time.

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Let Us Do

Observe the clocks and fill in the blanks.

Question 1. Observe the clocks and fill in the blanks.
Answer: Rani took 30 seconds to get out of her bed.
In simple words: Looking at both clocks, we can see Rani's time changed by 30 seconds.

Exam Tip: When finding the time difference between two clocks, focus on the second hand - it shows small time differences in seconds clearly.

Question 2. Observe the clocks and fill in the blanks.
Answer: Raghav took 25 seconds to move from his room to the kitchen.
In simple words: The two clocks show that 25 seconds passed as Raghav moved from one place to another.

Exam Tip: When the hour and minute hands stay in the same position, the change is in seconds only - read the seconds hand carefully.

Question 3. Observe the clocks and fill in the blanks.
Answer: Ritu took 15 seconds to pick up a piece of paper from the floor.
In simple words: From the first clock to the second clock, only 15 seconds went by.

Exam Tip: For very quick activities, you need to watch the second hand closely - it moves quickly and is easy to misread.

Question 4. Observe the clocks and fill in the blanks.
Answer: Raghu took 60 seconds to wash his spoon and plate.
In simple words: The time between the first clock and the second clock is exactly 60 seconds, which is the same as 1 minute.

Exam Tip: Remember that 60 seconds equals 1 minute - this is a key conversion to know when reading clock times.

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Draw the missing seconds hand on the clocks on the right side.

Question 1. Draw the missing seconds hand on the clocks on the right side.
Answer: Raghu took 20 seconds to read a sentence in his book. The second clock shows the second hand pointing to the 4 on the clock face (since each number on a clock represents 5 seconds, the 4 means 20 seconds).
In simple words: When the second hand points to a number, multiply that number by 5 to get the seconds. So the 4 means 4 × 5 = 20 seconds.

Exam Tip: On a clock, each number represents 5 seconds. Count by fives around the clock to find where the second hand should point for any number of seconds.

Question 2. Draw the missing seconds hand on the clocks on the right side.
Answer: Rani took 30 seconds to colour a rectangle. The second clock shows the second hand pointing to the 6 (since 6 × 5 = 30 seconds).
In simple words: The number 6 on the clock means 30 seconds have passed.

Exam Tip: The 6 is always at the bottom of a clock. If the second hand points there, it means exactly 30 seconds or half a minute.

Question 3. Draw the missing seconds hand on the clocks on the right side.
Answer: Raghav took 60 seconds to move from his home to the garden. The second clock shows the second hand pointing to the 12 (since the 12 represents 60 seconds or 1 full minute).
In simple words: When the second hand points straight up at the 12, exactly 1 minute (or 60 seconds) has gone by.

Exam Tip: The second hand pointing to 12 always means a complete minute has passed - this is a key landmark time to recognize instantly.

Question 4. Draw the missing seconds hand on the clocks on the right side.
Answer: Ritu took 40 seconds to wash a plate. The second clock shows the second hand pointing to the 8 (since 8 × 5 = 40 seconds).
In simple words: The number 8 on the clock represents 40 seconds.

Exam Tip: If you know how many seconds have passed, divide by 5 to find which number the second hand should point to.

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Let Us Do

Question 1. Use the double number line below to complete the conversions.
Answer: The double number line shows that 1 hour = 60 minutes and 2 hours = 120 minutes. Using this pattern, we can fill in: 2 hours = 2 × 60 = 120 minutes; 4 hours = 4 × 60 = 240 minutes; 7 hours = 7 × 60 = 420 minutes; 8 hours = 8 × 60 = 480 minutes; 9 hours = 9 × 60 = 540 minutes; 11 hours = 11 × 60 = 660 minutes; 12 hours = 12 × 60 = 720 minutes.
In simple words: To change hours to minutes, multiply the number of hours by 60. To change minutes back to hours, divide by 60.

Exam Tip: The double number line is a handy tool for seeing the pattern. Once you see it, you can use the same rule for any number of hours and minutes.

Question 1(b). Do as instructed. You can use the above double number line for the following conversions.
Answer:
(i) 1 hour 10 minutes = 70 minutes
(ii) 2 hours 45 minutes = 165 minutes
(iii) 3 hours 15 minutes = 195 minutes
(iv) 4 hours 20 minutes = 260 minutes
(v) 75 minutes = 1 hour 15 minutes
(vi) 150 minutes = 2 hours 30 minutes
(vii) 220 minutes = 3 hours 40 minutes
(viii) 390 minutes = 6 hours 30 minutes
In simple words: To convert hours and minutes to just minutes, change the hours to minutes first (multiply by 60), then add the extra minutes. To go the other way, divide the total minutes by 60 to find hours, and use what's left over as the minutes.

Exam Tip: When converting 75 minutes, divide: 75 ÷ 60 = 1 hour with 15 minutes remaining. Always check your work by converting back the other direction.

Question 1(c). Fill in the blanks in the double number line to complete the conversions.
Answer: The double number line for minutes to seconds shows: 1 minute = 60 seconds; 2 minutes = 120 seconds; 5 minutes = 300 seconds; 10 minutes = 600 seconds; 15 minutes = 900 seconds; 20 minutes = 1,200 seconds; 25 minutes = 1,500 seconds.
(i) 320 seconds = 5 minutes 20 seconds
(ii) 225 seconds = 3 minutes 45 seconds
(iii) 700 seconds = 11 minutes 40 seconds
(iv) 1,000 seconds = 16 minutes 40 seconds
(v) 10 minutes 13 seconds = 613 seconds
(vi) 4 minutes 8 seconds = 248 seconds
(vii) 15 minutes 40 seconds = 940 seconds
In simple words: Just like hours and minutes, minutes and seconds work the same way. Multiply minutes by 60 to get seconds, or divide seconds by 60 to get minutes and leftover seconds.

Exam Tip: When converting seconds like 320, divide by 60: 320 ÷ 60 = 5 with 20 left over, so the answer is 5 minutes 20 seconds. The leftover is always in the smaller unit.

Question 2. Raghav studies Mathematics, English, Hindi, and The World Around us subjects. He took 50 minutes to study each of the subjects. Find the total time taken in hours and minutes. Share your strategies with your class.
Answer: He studied four subjects, taking 50 minutes for each one. Total time spent studying = 50 × 4 = 200 minutes. Since 1 hour = 60 minutes, we divide: 200 ÷ 60 = 3 hours with 20 minutes left over. Total time = 3 hours 20 minutes.
In simple words: Multiply 50 minutes by 4 subjects to get 200 minutes. Then divide 200 by 60 to change it to hours and minutes.

Exam Tip: Always multiply or count first to get the total minutes, then convert to hours and minutes at the end. This reduces mistakes.

Question 3. Raghu left his house at 08:00 hours and arrived at his Nana ji's house at 09:05 hours. How long did he take to reach his house?
Answer: Start time: 08:00 A.M. Arrival time: 09:05 A.M. Time taken = 09:05 - 08:00 = 1 hour 5 minutes. Raghu took 1 hour 5 minutes to reach his grandpa's house.
In simple words: Subtract the start time from the arrival time to find how long the journey took.

Exam Tip: When the start and end times are close, subtract the hours first, then the minutes. If minutes in the start time are bigger, borrow 1 hour (60 minutes) and add it to the minutes.

Question 4. Jyoti went to play at 06:15 P.M. She came back after 1 hour 45 minutes. At what time did she reach home?
Answer: Start time: 06:15 P.M. Add 1 hour: 06:15 P.M. + 1 hour = 07:15 P.M. Add 45 minutes: 07:15 P.M. + 45 minutes = 08:00 P.M. Jyoti reached home at 08:00 P.M.
In simple words: When you need to add time to a starting time, add the hours first, then add the minutes. This gives you the final time.

Exam Tip: Break the time duration into hours and minutes and add them separately. This is easier than trying to add them all at once.

Question 5. Ragini took 1 hour 10 minutes to do her homework. She finished it at 09:40 P.M. What time did she start?
Answer: Finish time: 09:40 P.M. Subtract 1 hour: 09:40 P.M. - 1 hour = 08:40 P.M. Subtract 10 minutes: 08:40 P.M. - 10 minutes = 08:30 P.M. Ragini started her homework at 08:30 P.M.
In simple words: To find the start time, subtract the duration from the finish time. Subtract hours and minutes separately, just like you added them in the previous problem.

Exam Tip: When subtracting time, if the minutes being subtracted are larger than the current minutes, borrow 1 hour (60 minutes) first, then subtract.

Question 6. A group of children left for a picnic at 08:30 AM. They returned after 4 hours and 10 minutes. At what time did they return?
Answer: The starting time was 08:30 AM. We need to add 4 hours and 10 minutes to this. After adding 4 hours to 08:30 AM, we get 12:30 PM. Then we add the remaining 10 minutes to 12:30 PM, which gives us 12:40 PM. Therefore, the children returned at 12:40 PM.
In simple words: Start at 08:30 AM. Add 4 hours to get 12:30 PM. Then add 10 more minutes to get 12:40 PM.

Exam Tip: Always break the time addition into hours first, then minutes. This prevents errors when crossing from AM to PM.

Question 7. Raji started her homework at 06:00 PM. She finished her homework in 1 hour 30 minutes. At what time did she finish?
Answer: The starting time was 06:00 PM. We need to add 1 hour and 30 minutes to this. After adding 1 hour to 06:00 PM, we get 07:00 PM. Then we add the remaining 30 minutes to 07:00 PM, which gives us 07:30 PM. Therefore, Raji finished her homework at 07:30 PM.
In simple words: Start at 06:00 PM. Add 1 hour to get 07:00 PM. Then add 30 more minutes to get 07:30 PM.

Exam Tip: When adding minutes to a time, if the total minutes exceed 60, convert the extra minutes into an additional hour.

Question 8. Alya goes out to play at 05:30 PM and comes back after 1 hour 10 minutes. At what time does she come back?
Answer: The starting time was 05:30 PM. We need to add 1 hour and 10 minutes to this. After adding 1 hour to 05:30 PM, we get 06:30 PM. Then we add the remaining 10 minutes to 06:30 PM, which gives us 06:40 PM. Therefore, Alya comes back at 06:40 PM.
In simple words: Start at 05:30 PM. Add 1 hour to get 06:30 PM. Then add 10 more minutes to get 06:40 PM.

Exam Tip: Always note the starting time clearly and add hours and minutes separately to avoid confusion.

Question 9. If the lunch break of a school starts at 12:30 PM and ends in 35 minutes, what time will lunch end?
Answer: The starting time was 12:30 PM. We need to add 35 minutes to this. First, we add 30 minutes to 12:30 PM, which takes us to 01:00 PM. Then we add the remaining 5 minutes to 01:00 PM, which gives us 01:05 PM. Therefore, the lunch break will end at 01:05 PM.
In simple words: Start at 12:30 PM. Add 30 minutes to get 01:00 PM. Then add 5 more minutes to get 01:05 PM.

Exam Tip: When the minutes being added are less than 60, break them into smaller chunks to make the calculation easier - for example, add up to the next hour first, then add the rest.

Question 10. It is 08:35 PM right now. What time will it be after 8 hours and 25 minutes?
Answer: The starting time was 08:35 PM. We need to add 8 hours and 25 minutes to this. After adding 8 hours to 08:35 PM, we get 04:35 AM (the next day). Then we add the remaining 25 minutes to 04:35 AM, which gives us 05:00 AM. Therefore, the time will be 05:00 AM after 8 hours and 25 minutes.
In simple words: Start at 08:35 PM. Add 8 hours to get 04:35 AM the next day. Then add 25 more minutes to get 05:00 AM.

Exam Tip: When adding hours that cross from PM to AM, remember the time switches to the next day. Counting from PM to midnight is often the key step to get right.