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

Total Questions: 20

11. A box contains 2 white balls, 3 black balls and 4 red balls. What is the number of ways of drawing 3 balls from the box with at least one black ball?

Correct Answer: (c) 64
Solution:

12. During war one ship out of 5 was sunk on an average in making a certain voyage. What is the probability that exactly 3 out of 5 ships would arrive safely?

Correct Answer: (d) 128/625
Solution:

13. A card is drawn from a pack of 52 cards. A gambler bets that it is either a spade or an ace. The odds against his winning are

Correct Answer: (a) 9 : 4
Solution:

14. The coefficient of correlation between ages of husband and wife at the time of marriage for a given set of 100 couples was noted to be 0-7. Assume that all these couples survive to celebrate the silver jubilee of their marriage. The coefficient of correlation at that point of time will be

Correct Answer: (c) 0.7
Solution:

15. The completion of a construction job may be delayed due to strike. The probability of strike is 0 . 6. The probability that the construction job gets completed on time if there is no strike is 0 . 85 and the probability that the construction job gets completed on time if there is a strike is 0 . 35. What is the probability that the construction job will not be completed on time?

Correct Answer: (b) 0.45
Solution:

16. Which one of the following subjects shows highest variability of marks?

The mean and standard deviation (SD) of marks obtained by 50 students of a class in 4 subjects are given below:

SubjectMathematicsPhysicsChemistryBiology
Mean Marks40283836
SD15121416
Correct Answer: (d) Biology
Solution:

17. What is the coefficient of variation marks in Mathematics?

The mean and standard deviation (SD) of marks obtained by 50 students of a class in 4 subjects are given below:

SubjectMathematicsPhysicsChemistryBiology
Mean Marks40283836
SD15121416
Correct Answer: (a) 37.5%
Solution:C.V. of mathematics = 37.5%

18. What is the median of the distribution?

Consider the following grouped frequency distribution:

Class0–1010–2020–3030–4040–5050–60
Frequency124643
Correct Answer: (c) 35
Solution:
Class0–1010–2020–3030–4040–5050–60
fi124643
C.F.137131720

19. What is mean deviation about the median?

Consider the following grouped frequency distribution:

Class0–1010–2020–3030–4040–5050–60
Frequency124643
Correct Answer: (d) 10.5
Solution:
Class0-1010-2020-3030-4040-5050-60Total
xi51525354555
|xi - Me|30201001020
fi12464320
fi
|xi - Me|
30404004060210

20. What is the mean deviation about the mean?

Consider the following grouped frequency distribution:

Class0–1010–2020–3030–4040–5050–60
Frequency124643
Correct Answer: (b) 10.65
Solution:
Class0-1010-2020-3030-4040-5050-60Total
fi12464320
xi51525354555
xi fi530100210180165690
|xi −ˣ̄|29.519.59.50.510.520.5
fi |xi −ˣ̄|29.5393834261.5213