CAT 1991 — QA Question 27
Answer the following questions based on the information given below:
There were a hundred schools in a town. Of these, the number of schools having a play – ground was 30, and these schools had neither a library nor a laboratory. The number of schools having a laboratory alone was twice the number of those having a library only. The number of schools having a laboratory as well as a library was one fourth the number of those having a laboratory alone. The number of schools having either a laboratory or a library or both was 35.
A player rolls a die and receives the same number of rupees as the number of dots on the face that turns up. What should the player pay for each roll if he wants to make a profit of one rupee per throw of the die in the long run?
Answer & solution
Rs. 2.50
- B
Rs. 2
- C
Rs. 3.50
- D
Rs. 4
Since in the long run the probability of each number appearing is the same, we can say in ‘n’ throws one can get 1, 2, 3, 4, 5 and 6, n/6 times each.
Hence he would earn (1 + 2 + 3 + 4 + 5 + 6)n/6 = Rs. 7n/2 = Rs. 3.5n.
∴ His average earning for each through is 3.5n/n = Rs. 3.5
In order to make a profit of 1 Re. per throw his cost for the each through should be = 3.5 – 1 = Rs. 2.50
Hence, option (a).