The average number of pages Marion read in a certain number of days was 12. In the next five days, Marion read another 100 pages. As a result, the average number of pages she read increased to 16. How many days did Marion read in total?
|
At first |
In the end |
Number |
1 u |
1 u + 5 |
Value |
12 |
16 |
Number x value |
12 u |
16 u + 80 |
Number of days that Marion read at first = 1 u
Number of pages that Marion read at first
= 1 u x 12
= 12 u
Number of pages that Marion read in the end = 12 u + 100
Number of days that Marion read in the end = 1 u + 5
Number of pages that Marion read in the end
= 16 x (1 u + 5)
= 16 u + 80
16 u + 80 = 12 u + 100
16 u - 12 u = 100 - 80
4 u = 20
1 u = 20 ÷ 4 = 5
Number of days that Marion read in the end
= 1 u + 5
= 5 + 5
= 10
Answer(s): 10