Q11. If 40% of boys opted for maths and 60% of girls opted for maths, then what is the

probability that maths is chosen if half of the class's population is girls? Ans 0.5

Q12. A problem is given to 5 students P, Q, R, S, T. If the probability of solving the problemindividually is 1/2, 1/3, 2/3, 1/5, 1/6 respectively, then find the probability that the problem

is solved. Ans. 0.37

Q13.In badminton practice session, the probability that the player A serves properly is 0.8 andthat the player B serves properly is 0.9. If there are only two players, then find the

probability that it is serves properly. Ans. 0.85

Q14.Let there be two newly launched phones A and B. The probability that phone A has goodbattery life is 0.7 and the probability that phone B has good battery life is 0.8. Then find theprobability that a phone has a good battery life. Ans. 0.75

Q15.Two boxes containing candies re placed on a table. The boxes are labelled B1 and B2. BoxB1 contains 7 cinnamon candies and 4 ginger candies. Box B2 contains 3 cinnamon candiesand 10 pepper candies. The boxes are arranged so that the probability of selecting boxB1 is 13 and the probability of selecting box B2 is 23. Suresh is blindfolded and asked toselect a candy. He will win a colour TV if he selects a cinnamon candy. What is the

probability that Suresh will win the TV (that is, she will select a cinnamon candy)? Ans. 13/33

Q16.Suppose box A contains 4 red and 5 blue coins and box B contains 6 red and 3 blue coins.A coin is chosen at random from the box A and placed in box B. Finally, a coin is chosen atrandom from among those now in box B. What is the probability a blue coin was transferredfrom box A to box B given that the coin chosen from box B is red?

Q17. At a certain university, 4% of men are over 6 feet tall and 1% of women are over 6 feet tall.

The total student population is divided in the ratio 3:2 in favour of women. If a student is

selected at random from among all those over six feet tall, what is the probability that the student is woman? Ans 3/11

Q18.Three companies A, B and C supply 25%, 35% and 40% of the notebooks to a school. Pastexperience shows that 5%, 4% and 2% of the notebooks produced by these companies aredefective. If a notebook was found to be defective, what is the probability that the notebookwas supplied by A. Ans. 25/69

Q19.A box of cartridges contains 30 cartridges, of which 6 are defective. If 3 of the cartridges are removed from the box in succession without replacement, what is the probability that all the3 cartridges are defective? Ans.(6*5*4)/(30*29*28)

20. From a pack of 52 cards. Three cards are drawn one by one without replacement. Find the probability that each time it is a card of spade. Ans. (11/850)