The average number of pages Tina read in a certain number of days was 13. In the next four days, Tina read another 74 pages. As a result, the average number of pages she read increased to 15. How many days did Tina read in total?
| |
At first |
In the end |
| Number |
1 u |
1 u + 4 |
| Value |
13 |
15 |
| Number x value |
13 u |
15 u + 60 |
Number of days that Tina read at first = 1 u
Number of pages that Tina read at first
= 1 u x 13
= 13 u
Number of pages that Tina read in the end = 13 u + 74
Number of days that Tina read in the end = 1 u + 4
Number of pages that Tina read in the end
= 15 x (1 u + 4)
= 15 u + 60
15 u + 60 = 13 u + 74
15 u - 13 u = 74 - 60
2 u = 14
1 u = 14 ÷ 2 = 7
Number of days that Tina read in the end
= 1 u + 4
= 7 + 4
= 11
Answer(s): 11
