Question

A typist can type a sheet in 5 minutes. another types at the rate of 10 sheet an hour, and a third typist types 3/4th number of sheets as the second in half the time. find the average speed per typist per minute.

Answer 1

1st typist can type a sheet in 5 minutes
∴ in 60 minutes , 1st typist can type number of sheets = 60/5 = 12
∴ 1st typist can type 12 sheets in a hour


2nd typist can type 10 sheets in a hour

3rd typist types 3/the number of sheets as the second half the time
Means in 60/2 minutes , 3rd typist can type 3/4th of 10 sheets
in 30 minutes , 3rd typist can type 15/2 sheets
so, 3rd typist can type 15 sheets in 60 minutes


Now, average speed = total typings/total time
= (12 + 10 + 15)/(60 + 60 + 60)
= 37/180

Hence answer is 37/180

Answer 2

Solution :-

1st typist -

In 5 minutes 1st typist types = 1 sheet

In 1 minute 1st typist will type = 1/5 sheet

= 1/5 sheet per minute

2nd typist -

In 60 minutes 2nd typist types = 10 sheets

In 1 minutes 2nd typist will type = 10/60

= 1/6 sheet per minute

3rd typist -

3rd typist types 3/4 number of sheets as compared to the 2nd typist in half the time. 

⇒ 3/4 of 10 = (10*3)/4

= 7 1/2 sheets in 30 minutes

Then, in 60 minutes = (7 1/2)*2

= 15 sheets

In 60 minutes the 3rd typist types = 15 sheets

In 1 minute the 3rd will type = 15/60

= 1/4 sheet per minute

Average speed of 1st typist = 1/5 sheet per minute

Average speed of 2nd typist = 1/6 sheet per minute

Average speed of 3rd typist = 1/4 sheet per minute

Answer.