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

Total Questions: 20

1. A coin is biased so that heads comes up thrice as likely as tails. For three independent tosses of a coin, what is the probability of getting at most two tails?

Correct Answer: (d) 0.98
Solution:

2. A bag contains 20 books out of which 5 are defective. If 3 of the books are selected at random and removed from the bag in succession without replacement, then what is the probability that all three books are defective?

Correct Answer: (a) 0.009
Solution:

3. The median of the observations 22, 24, 33, 37, x + 1, x + 3, 46, 47, 57, 58 in ascending order is 42. What are the values of 5th and 6th observations respectively?

Correct Answer: (b) 41, 43
Solution:

4. Arithmetic mean of 10 observations is 60 and sum of squares of deviations from 50 is 5000. What is the standard deviation of the observations?

Correct Answer: (a) 20
Solution:

5. If p and q are the roots of the equation x² − 30x + 221 = 0, what is the value of p³ q³?

Correct Answer: (b) 7110
Solution:

6. For the variables x and y, the two regression lines are 6x + y = 30 and 3x + 2y = 25?

What are the values of x̄, ȳ and r respectively?

Correct Answer: (c) 35/9, 20/3, -0.5
Solution:

7. The class marks in a frequency table are given to be 5, 10, 15, 20, 25, 30, 35, 40, 45, 50. The class limits of the first five classes are:

Correct Answer: (b) 2.5-7.5, 7.5-12.5, 12.5-17.5,17.5-22.5, 22.5-27.5
Solution:

8. The mean of 5 observations is 4.4 and variance is 8.24. If three of the five observations are 1, 2 and 6, then what are the other two observations?

Correct Answer: (b) 9, 4
Solution:

9. If a coin is tossed till the first head appears, then what will be the sample space?

Correct Answer: (a)
Solution:A coin is tossed till the first head appears, then the sample space will be
= {H}

10. Consider the following discrete frequency distribution:

What is the value of median of the distribution?

Correct Answer: (b) 5
Solution: