CAT 1996 — QA Question 30
Direction: Answer the questions based on the following information.
A salesman enters the quantity sold and the price into the computer. Both the numbers are two-digit numbers. But, by mistake, both the numbers were entered with their digits interchanged. The total sales value remained the same, i.e. Rs. 1,148, but the inventory reduced by 54.
A man has 9 friends: 4 boys and 5 girls. In how many ways can he invite them, if there have to be exactly 3 girls in the invitees?
Answer & solution
- A
320
160
- C
80
- D
200
Out of the 5 girls, 3 girls can be invited in 5C3 ways. Nothing is mentioned about the number of boys that he has to invite. He can invite one, two, three, four or even no boys. Each boy can be invited or not. He can invite them in 24 ways. Thus, the total number of ways is 5C3 × (2)4 = 10 × 16 = 160.
Hence, option (b).