Respuesta :
The number of files sorted in the first one and a half hours of sorting is 945.
Here, we are given that a group of clerks must sort 1775 files.
Each clerk sorts at a constant rate of 30 files per hour.
Let the number of clerks who start working initially be x.
Thus, they will sort 30x files in the first hour.
After the first hour, let the number of clerks who stop working be a
Thus, the number of files sorted in the second hour will be 30(x - a)
Similarly, the number of files sorted in the third hour will be 30(x - 2a)x
In the last 10 minutes, the number of files sorted will be 5(x - 3a)
Thus, we can form the following equation-
30x + 30(x - a) + 30(x - 2a) + 5(x - 3a) = 1775
30x + 30x - 30a + 30x - 60a + 5x - 15a = 1775
95x - 105a = 1775
19x - 21a = 355
x = (355 + 21a)/ 19
since x and a both have to be integers, (355 + 21a) must be divisible by 19.
This is the case when a = 3
⇒ x = (355 + 21*3)/ 19
x = 418/ 9
x = 22
Now, the number of files sorted in first one and a half hours will be-
30x + 15(x - a)
= 30*22 + 15(22 - 3)
= 660 + 15*19
= 660 + 285
= 945
Thus, the number of files sorted in the first one and a half hours of sorting is 945.
Learn more about remainders here-
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