word problem

[sud21]

The average of the data in 12 weeks in a certain company is n. If 24, the data in a certain week, is replaced by a number, the average became n-3/4. What is the number?
15,18,23,24,33

[rijul007]

The average of the data in 12 weeks in a certain company is n. If 24, the data in a certain week, is replaced by a number, the average became n-3/4. What is the number?
15,18,23,24,33

12n - x + 24 = 12(n-3/4)
12n - x + 24 = 12n - 9
x-24 = 9
x = 33

Option E

[neelgandham]

The average of the data in 12 weeks in a certain company is n. If 24, the data in a certain week, is replaced by a number, the average became n-3/4. What is the number?
1)15
2)18
3)23
4)24
5)33

Old Total = 12*n
New Total = 12(n-0.75)
Old Total - 24 + X = New Total (Where X = The number which replaced 24)
12*n - 24 + X = 12(n-0.75)
X = 15
Option A

[GMATGuruNY]

The average of the data in 12 weeks in a certain company is n. If 24, the data in a certain week, is replaced by a number, the average became n-3/4. What is the number?
15,18,23,24,33

Sum = number*average.
Since the number of days = 12 and the decrease in the average = 3/4, the decrease in the sum = 12(3/4) = 9.
Thus, the new number = 24-9 = 15.

The correct answer is A.