Answer: C.186
Step-by-step explanation:
1. You know that he read 6 books when he was 6 years old and every year he doubled the number of books he read the previous year.
2. Let's call [tex]n[/tex] the number of book he read each year and [tex]n_t[/tex] the number of books he read between the ages of 6 and 10, then:
- At 6 years old:
[tex]n=6[/tex]
- At 7 years old:
[tex]n=6*2=12[/tex]
- At 8 years old:
[tex]n=12*2=24[/tex]
- At 9 years old:
[tex]n=24*2=48[/tex]
- At 10 years old:
[tex]n=96[/tex]
The total books he read between the ages of 6 and 10 is:
[tex]n_t=6+12+24+48+96\\n_t=186[/tex]
