Question

Joshua likes to read. He read 6 books when he was 6 years old. Every year he doubled the number of books he read the previous year. How many books did he read between the ages 6 and 10?

Answer 1

When Joshua Is 6 he reads 6 books, when he is 7 he reads 12 books, when he turns 8, he reads 24 books, when he turns 9 he reads 48 books, when Joshua turns 10 he reads 96 books

6+12+24+48+96=186
The answer is C

Answer 2

186

Explanation:

Joshua reads 6 books when he was 6 years old. Every year he doubled the number of books he read the previous year.

The series will be,

`6,12,18,......`

This is in Geometric Progression. With initial term as 6 and common ratio as 2.

As we have to find the number of books he read from 6 year to 10 years i.e we have to find the sum of the series upto 5th term.

We know,

`S_n=(a(r^n-1))/(r-1)=(6(2^5-1))/(2-1)=186`