Probability (SSC)

Total Questions: 64

21. A box contains 10 identical electronic components of which 4 are defective. If 3 components are selected at random from the box in succession, without replacing the units already drawn, what is the probability that two components of the selected components are defective?

Correct Answer: (a)
Solution:

22. 29 defective pens are accidentally mixed with 319 good ones. It is not possible to just look at a pen and tell whether or not it is defective. One pen is taken out at random from this lot. Determining the probability that the pen is taken out is a good one.

Correct Answer: (b)
Solution:

23. Calculating the probability of selecting a black card or a six number from a deck of 52 cards.

Correct Answer: (a)
Solution:

24. Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

Correct Answer: (c)
Solution:

25. A bag contains 6 red balls and 4 blue balls. 2 balls are drawn at random. Find the probability that they are of the same color?

Correct Answer: (c)
Solution:

26. A student appeared for a sectional test containing 10 questions. A reviewer checks the answers and finds that the student answered three questions wrong. What is the probability that the sixth reviewed question is the last wrong question?

Correct Answer: (a)
Solution:

27. A bag contains 4 white balls and 2 black balls. Another bag contains 3 white balls and 5 black balls. If one ball is drawn from each bag, what is the probability that both the balls are black.

Correct Answer: (c)
Solution:

28. A bag contains white, black and red balls only. A ball is drawn at random from the bag. If the probability of getting a white ball is 3/10 and that of a black ball 2/5, then find the probability of getting is a red ball. If the bag contains 20 black balls, then find the total number of balls in the bag.

Correct Answer: (b)
Solution:

29. A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random from the bag. The probability that all of them are red, is:

Correct Answer: (a)
Solution:

30. The probability of a shooter hitting a target is 0.75 . How many minimum number of times must he/she fire so that the probability of hitting a target at least once is more than 0.99 ?

Correct Answer: (a) 4
Solution: