Mathematics (NDA/NA SOLVED PAPER 2022-II) (101 to 120)

Total Questions: 20

1. Let x be the mean of squares of first n natural numbers and y be the square of mean of first n natural numbers.

if x/y = 55/42, then what is the value of n?

Correct Answer: (c) 27
Solution:

2. What is the probability of getting a composite number in the list of natural numbers from 1 to 50?

Correct Answer: (b) 17/25
Solution:

3. If n > 7 then what is the probability that C(n, 7) is a multiple of 7?

Correct Answer: (a) 0
Solution:

4. Two numbers x and y are chosen at random from a set of first 10 natural numbers. What is the probability that ( x + y) is divisible by 4?

Correct Answer: (b) 2/9
Solution:

5. A number x is chosen at random from first n natural numbers. What is the probability that the number chosen satisfies x + 1/x > 2?

Correct Answer: (c) (n - 1)/n
Solution:

6. Three fair dice are tossed once, What is the probability that they show different numbers that are in AP?

Correct Answer: (b) 1/18
Solution:

7. If P(A) = 0 . 5, P(B) = 0 . 7 and P(A ∩ B)= 0 . 3 , then what is the value of P( A' ∩ B') + P(A '∩ B) + P(A ∩ B)?

Correct Answer: (b) 0.7
Solution:

8. Five coins are tossed once. What is the probability of getting at most four tails?

Correct Answer: (a) 31/32
Solution:

9. Three fair dice are thrown. What is the probability of getting a total greater than or equal to 15?

Correct Answer: (d) 5/54
Solution:

10. The probability that a person hits a target is 0 . 5. What is the probability of at least one hit in 4 shots?

Correct Answer: (c) 15/16
Solution: