The average number of visitors of a library in the first 4 days of a week was 58. The average for the 2nd, 3rd, 4th and 5th days was 60. If the number of visitors on the 1st and 5th days were in the ratio 7:8 then what is the number of visitors on the 5th day of the library?
58
60
56
64
Explanation:
If number of visitors on 1st, 2nd, 3rd, 4th & 5th day are a, b, c, d & e respectively, then
=> a+b+c+d=58 $\times$ 4=232 ----(i)
=> b+c+d+e=60 $\times$ 4=240 ----(ii)
Subtracting (i) from (ii), we get:
=> e-a = 8 ---(iii)
Given, a/e=7/8 ---(iv)
So from (iii) & (iv), a=56, e=64.