Mathematics NDA/NA SOLVED PAPER 2017 (II) (101 to 120)

Total Questions: 20

11. What is the probability that at least two persons out of a group of three persons were born in the same month (disregard year)?

Correct Answer: (b) 17/72
Solution:

12. Simplify the question?

Correct Answer: (c) X = −8 + 0.2Y
Solution:

13. Simplify the question?

Correct Answer: (a) 1/12
Solution:

14. The following table gives the monthly expenditure of two families :

In construction a pie diagram to theabove data, the radii of the circles are to be chosen by which one of the following ratios?

Correct Answer: (b) 10 : 9
Solution:

15. If a variable takes values 0, 1, 2, 3,..….,n with frequencies 1, C(n, 1), C(n, 2), C(n, 3),...........,C(n, n) respectively, then the arithmetic mean is:

Correct Answer: (d) n/2
Solution:

16. In a multiple-choice test, an examinee either knows the correct answer with probability p, or guesses with probability 1 - p. The probability of answering a question correctly is 1/m, if he or she merely guesses. If the examinee answers a question correctly, the probability that he or she really knows the answer is:

Correct Answer: (b)
Solution:

17. If x₁ and x₂ are positive quantities, then the condition for the difference between the arithmetic mean and the geometric mean to be greater than 1 is:

Correct Answer: (c) |√x₁ − √x₂| > √2
Solution:

18. Consider the following statements :

1. Variance is unaffected by change of origin and change of scale.
2. Coefficient of variance is independent of the unit of observations.
Which of the statements given above is/are correct?

Correct Answer: (b) 2 only
Solution:

Only statement 2 is correct

19. Five sticks of length 1, 3, 5, 7 and 9 feet are given. Three of these sticks are selected at random. What is the probability that the selected sticks can form a triangle?

Correct Answer: (c) 0.3
Solution:

20. The coefficient of correlation when coefficients of regression are 0.2 and 1.8 is:

Correct Answer: (c) 0.6
Solution: