Question

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 8 : 9. Then what is the number of visitors on the 5th day of the library ?

A) 54
B) 64
C) 68
D) 72

Answer 1

Answer:

The answer is B

Step-by-step explanation:

There is only going to be aa slight increase between the average visitors because the ratio is 8:9

Answer 2

Given :

Average number of visitors in the first 4 days = 58

Average for 2nd, 3rd, 4th and 5th days = 60

Ratio of first and 5th day = 8:9

To find :

Number of visitors on the 5th day of the library =?

Solution:

Average number of visitors in the first 4 days :

$\dfrac{a+b+c+d}{4}=58\\\\a+b+c+d=58\times 4=232$---------------------(1)

Average number of visitors for 2nd, 3rd, 4th and 5th days :

$\dfrac{b+c+d+e}{4}=60\\\\b+c+d+e=60\times 4\\\\b+c+d+e=240$---------------------(2)

From eq(1) and eq(2) we get :

$b+c+d+e-(a+b+c+d)=240-232\\\\e-a=8$

Since ratio of e: a = 9:8

So, it becomes:

$9x-8x=8\\\\x=8$

So, the number of visitors on the 5th day would be

$9x=9\times 8=72$

Hence, Option (d) is correct.