Mathematics NDA/NA SOLVED PAPER 2018 (II) (101 to 120)

Total Questions: 20

11. If ๐‘ฅแตข > 0 , ๐‘ฆ ๐‘– > 0 โ€‰ ( ๐‘– = 1 , 2 , 3 , . . . , ๐‘› ) are the values of two variables ๐‘‹ and ๐‘Œ with geometric means P and Q respectively, then the geometric mean of X/Y is:

Correct Answer: (a) P/Q
Solution:

12. If probability of simultaneous occurrence of two events A and B is p and the probability that exactly one of A, B occurs is q, then which of the following is/are correct?

Correct Answer: (c) Both 1 and 2
Solution:

13. If the regression coefficient of Y on X is โˆ’6 and the correlation coefficient between X and Y is -1/2, then the regression coefficient of X on Y would be:

Correct Answer: (b) -1/24
Solution:

14. The set of bivariate observations (xโ‚, yโ‚), (xโ‚‚, yโ‚‚).........(xโ‚™, yโ‚™) are such that all the values are distinct and all the observations fall on a straight line with non-zero slope. Then the possible values of the correlation coefficient between x and y are:

Correct Answer: (d) โˆ’1 and 1
Solution:

Given that, All the observations fall on a straight line with non-zero, slope then if slope is positive then r = 1
and if slope is negative then r = โˆ’1 So, values of the correlation coefficient
between x and y are โˆ’1 and 1.

15. Find the answer of given equation?

Correct Answer: (c) 30/121
Solution:

16. Answer the following question?

Correct Answer: (d) None of the above
Solution:

17. Three dice having digits 1, 2, 3, 4, 5 and 6 on their faces are marked I, II, and III and rolled. Let x, y and z represent the number on die-I, die-II and die-III, respectively. What is the number of possible outcomes such that x > y > z?

Correct Answer: (d) 20
Solution:

18. Which one of the following can be obtained from an ogive?

Correct Answer: (b) Median
Solution:

We know that, median is always calculated from less than or more than type ogive curve where both curve cuts each other that point median.

19. In any discrete series (when all values are not same), if x represents mean deviation about mean and y represents standard deviation, then:

which one of the following is correct?
(a) y > x
(b) y < x
(c) x = y
(d) x < y

Correct Answer: (d)
Solution:

20. In which one of the following cases would you expect to get a negative correlation?

Correct Answer: (c) Insurance companies profits and the number of claims they have to pay
Solution:

In negative correlation, if x is increases then y is decreases by checking options Insurance companies profits and the number of claims they have to pay are negatively correlated.