Answer:
6
3/5
Step-by-step explanation:
The total of all books is 1.
For Fiction to be 3 times more than Biographies.
Biographies have to have same probability to be chosen as poetry.
So to solve for the probability to choose Fiction is 3 × 1/5 = 3/5
The number of fiction books is solved with 10 × 3/5 = 6
