Question
Question: A class contains three girls and four boys. Every Saturday five students go on a picnic, a different...
A class contains three girls and four boys. Every Saturday five students go on a picnic, a different group being sent each week. During the picnic, each girl in the group is given a doll by the accompanying teacher. After all possible groups of five have gone once, the total number of dolls the girls have got, is
A
27
B
11
C
21
D
45
Answer
45
Explanation
Solution
Sol. Explanation:
Observe the following table for various trips
No. of girls No. of boys N.o trips No. dolls
1 4 3C1× 4C4 = 3 3
2 3 3C2 × 4C3 = 12 2 × 12 = 24
3 2 3C3 × 4C2 = 6 3 × 6 = 18
Total number of dolls = 3 + 24 + 18 = 45