CBSE Class 9 Mathematics Number System Assignment Set J

Question. The product of 100 real numbers is -100. AT LEAST how many of these 100 real numbers must be positive?
(a) 99
(b) 2
(c) 1
(d) none

Answer : C

Question. For which of these values of y will 2y be an irrational number?
(a) y = √49
(b) y = -2/13
(c) y = 22/7
(d) y = √8

Answer : D

Question. I have two leaking taps in my kitchen. The first tap drips once every 8 seconds and the second one drips once every 12 seconds. When any one tap drips alone, I call it a 'SINGLE DRIP' and when both drip simultaneously, I call it a 'DOUBLE DRIP'.
The number of 'SINGLE DRIPS' in an interval of 100 seconds following a 'DOUBLE DRIP' will be
(a) 3
(b) 7
(c) 12
(d) 18

Answer : C

Question. Shyam's father is 6 times as old as Shyam. Shyam's mother is 25 years old. The average age of this family of three is 20 years. How old is Shyam?
(a) 15 years
(b) 10 years
(c) 7 years
(d) 5 years

Answer : D

Question. The average of the 1st five natural numbers is
(a) 2.25
(b) 2.5
(c) 3
(d) 3.5

Answer : C

Question. What will be the remainder when 46788 is divided by 5?
(a) 1
(b) 2
(c) 3
(d) 4

Answer : A

Question. See the following matchstick patterns.
How many matchsticks would be required to make a similar 10 × 10 square pattern?

(a) 100
(b) 200
(c) 220
(d) 500

Answer : C

Question. The pattern of numbers below forms a special sequence called the Fibonacci sequence. Study the first 7 numbers given below and understand the pattern 1,1,2,3,5,8,13 ...........
What could the next two numbers of the sequence be?
(a) 18 and 23
(b) 18 and 31
(c) 21 and 26
(d) 21 and 34

Answer : D

Question. Mr. Malkani owns a hotel with exactly 100 rooms. The first room is numbered as 1, the second one as 2 and so on. However, being a superstitious man, he has taken care that no room in his hotel bears the number 13 or any of its multiples.
What is the room number of the 100th room in the hotel?
(a) 87
(b) 100
(c) 107
(d) 108

Answer : D

Question. If x + 5 is a multiple of 3, which of the following MUST be a multiple of 9?
(a) x² + 25
(b) 3x + 5
(c) (x + 5)(x + 5)
(d) (x + 5)(x + 9)

Answer : C

Question. A certain whole number is multiplied by 90 and then divided by 2. Which of the following could be the result?
(a) 33228
(b) 52320
(c) 61635
(d) 26550

Answer : D

Question. Adil's bathroom has two taps next to each other and a bucket is kept under them. Tap 1 alone (at full flow) can fill HALF the bucket in 2 minutes and Tap 2 alone (at full flow) can fill HALF the bucket in 3 minutes.
If both taps are turned on (to full flow), in how much time will the bucket get filled completely?
(a) 2 minutes 24 seconds
(b) 2 minutes 30 seconds
(c) 5 minutes
(d) 10 minutes

Answer : A

Question. 2. 31 × 10^-3 can be written as

(a) -69. 3
(b) -2310
(c) 0. 00231
(d) 1/2.31 × 10³

Answer : C

Question. 3 ×10³ / 6 ×10⁴ is
(a) 0. 5 × (10)^3/4
(b) 0. 5 × 10
(c) (2 × 10)^-1 
(d) 2 × (10)^-1

Answer : C

Question. A number N is increased by 100%. The resulting number is then decreased by 100%. The final result will be
(a) 50N
(b) N
(c) N²
(d) 0

Answer : D