Mathematics NDA/NA SOLVED PAPER 2019 (II) (101 to 120)

Total Questions: 20

11. Two dice are thrown simultaneously. What is the probability that the sum of the numbers appearing on them is a prime number?

Correct Answer: (a) 5/12
Solution:

12. If 5 of a Company’s 10 delivery trucks do not meet emission standards and 3 of them are chosen for inspection, then what is the probability that none of the trucks chosen will meet emission standards?

Correct Answer: (c) 1/12
Solution:

13. There are 3 coins in a box. One is a two-headed coin; another is a fair coin; and third is biased coin that comes up heads 75% of time. When one of the three coins is selected at random and flipped, it shows heads. What is the probability that it was the two-headed coin?

Correct Answer: (c) 4/9
Solution:

14. Consider the following statements:

Correct Answer: (b) Only 2
Solution:

15. If a fair die is rolled 4 times, then what is the probability that there are exactly 2 sixes?

Correct Answer: (b) 25/216
Solution:

16. Mean of 100 observations is 50 and standard deviation is 10. If 5 is added to each observation, then what will be the new mean and new standard deviation respectively?

Correct Answer: (c) 55, 10
Solution:

17. If the range of a set of observations on a variable X is known to be 25 and if Y = 40 + 3X, then what is the range of the set of corresponding observations onY ?

Correct Answer: (c) 75
Solution:

18. If V is the variance and M is the mean of first 15 natural numbers, then what is V + M² equal to?

Correct Answer: (c) 248/3
Solution:

19. A car travels first 60 km at a speed of 3 v km/h and travels next 60 km at 2 v km/h. What is the average speed of the car?

Correct Answer: (b) 2.4 v km/h
Solution:

20. The mean weight of 150 students in a certain class is 60 kg. The mean weight of boys is 70 kg and that of girls is 55 kg. What are the number of boys and girls respectively in the class?

Correct Answer: (b) 50 and 100
Solution: