how do you solve this?

Question

It takes 5 hours for 3 typists to type a set of letters. How long would it take 8 typists to type the letters?

Answer 1

If 3 typists need 5 hours, then 1 typist needs three times longer time period which is 15 hours.

but, if you have 8 typists, then they will need 8 times shorter time then 1 typist to do the job which is 15/8 hours

the answer: 1 hour 1/8 of an hour or 15/8 hours or 1.88 hours

Answer 2

first, an assumption must be made (or, it has to be implied) that each typist would uniformly accomplish the job, working alone, in x hours... let the hourly rate for each typist be 1/x; then, working together, the job will be accomplished by 3 typists at the hourly rate of 1/5; that is,

3(1/x) = 1/5

which yields x = 15

i.e. each typist, working alone can complete the job in 15 hours... so, now, for 8 typists, working together, let y be the number of hours to accomplish the job; so,

8(1/15) = 1/y

which yields y = 15/8

i.e. the job can be completed by 8 typists, working together, in under 2 hours.

Answer 3

Approximately 2 hours

Answer 4

1.875 hours, 1 hour and 52min, 30 sec