A and B play a game where each is asked to select a number from 1 to 5. If the two numbers match, both of them win a prize. The probability that they will not win a prize in a single trial is
Answer: B Total number of ways in which both of them can select a number each = 5*5 =25 Probability that they win the prize = 1*1/25 = 1/25. Probability that they do not win a prize = 1- 1/25 = 24/25.
Q. No. 14:
An anti- aircraft gun can take a maximum of four shots at an enemy plane moving away from it. The probability of hitting the plane at the first, second, third and fourth shots are 0.4, 0.3, 0.2 and 0.1 respectively. What is the probability that the plane is hit when all the four shots are fired?
Answer: A Total numbers of cards = 200 {and not 99} multiples of three = 66 The required probability =0.66
Q. No. 16:
A box contain 9 red toys, 7 green toys and 9 blue toys. Each ball is of a different size. The probability that the red ball being selected is the smallest red toy, is
Answer: B We can get 2 tails in 3C2ways. We can get 3 tails in exactly one way. Thus, required probability = (3+1)/8 = 1/2
Q. No. 18:
The probability that a arrow fired from a point will hit the target is 1/4. Three such arrows are fired simultaneously towards the target from that very point. What is the probability that the target will be hit?
Answer: D Probability of a arrow not hitting the target = 3/4 Probability that none of the 3 arrow will hit the target = (3/4)3 = 27/64 Probability that the target will hit at least once = 1 - 27/64 = 37/64