The average number of pages Barbara read in a certain number of days was 15. In the next five days, Barbara read another 97 pages. As a result, the average number of pages she read increased to 17. How many days did Barbara read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 5 |
| Value |
15 |
17 |
| Number x value |
15 u |
17 u + 85 |
Number of days that Barbara read at first = 1 u
Number of pages that Barbara read at first
= 1 u x 15
= 15 u
Number of pages that Barbara read in the end = 15 u + 97
Number of days that Barbara read in the end = 1 u + 5
Number of pages that Barbara read in the end
= 17 x (1 u + 5)
= 17 u + 85
17 u + 85 = 15 u + 97
17 u - 15 u = 97 - 85
2 u = 12
1 u = 12 ÷ 2 = 6
Number of days that Barbara read in the end
= 1 u + 5
= 6 + 5
= 11
Answer(s): 11
