CBSE Class 7 Mathematics Data Handling Worksheet Set 03

Question 1. The mean of 6,8,5,x and 4 is 7. Find the value of x.
Answer:
We know there are 5 numbers in total, and their average (mean) is 7.
First, find the sum of all 5 numbers by multiplying the mean by 5:
\( \text{Total Sum} = 7 \times 5 = 35 \)

Now, find the sum of the four known numbers:
\( 6 + 8 + 5 + 4 = 23 \)

To find the value of \( x \), subtract this sum from the total sum:
\( x = 35 - 23 = 12 \)

Therefore, the value of \( x \) is 12.
In simple words: Multiply the average (7) by how many numbers there are (5) to get 35. Subtract the other numbers to find that \( x \) is 12.

Exam Tip: Always start by multiplying the average by the count of items to find the total sum.

Question 2. The results of pass percentage of Class X and XII in C.B.S.E. examination for 5 years are given in the following table:
Year 2001-02 2002-03 2003-04 2004-05 2005-06
X 90 95 90 80 98
XII 95 80 85 90 95
Draw a double bar-graph to represent the data. Also find the mean of the pass percentage of Class-X and XII respectively for the five years. Which class had a better performance in those five years- class X or XII?
Answer:
Let us first find the mean pass percentage for both Class X and Class XII over the five-year period.

- For Class X:
\( \text{Mean of Class X} = \frac{90 + 95 + 90 + 80 + 98}{5} = \frac{453}{5} = 90.6 \% \)

- For Class XII:
\( \text{Mean of Class XII} = \frac{95 + 80 + 85 + 90 + 95}{5} = \frac{445}{5} = 89 \% \)

Comparing the two averages, Class X has a higher mean of \( 90.6 \% \) compared to \( 89 \% \) for Class XII. This means Class X performed better over these five years.

In simple words: Class X had a higher average score of \( 90.6 \% \), so it performed better than Class XII overall.

Exam Tip: Always state the final comparison clearly in a sentence to secure full marks on comparison questions.

Question 3. Favourite Sport: Cricket Basket-Ball Swimming Hockey Athletics
Watching 1240 470 510 423 250
Participating 620 320 320 250 105
Draw a double bar graph choosing appropriate scale. What do you infer from the data?
(i) Which sport is most popular?
(ii) What is more preferred: watching or participating in sports?
Answer:
We can find the answers directly from the given data table:
(i) Cricket is the most popular sport. It has the highest number of viewers (1240) and active players (620).
(ii) People clearly prefer watching sports over participating in them. The numbers for watching are much higher for every sport.

In simple words: Cricket is the favorite sport. Most people prefer to sit and watch sports rather than play them.

Exam Tip: To find the most popular category, look for the tallest bar in your double bar graph.