The question asks for the rate of toys per hour.
So we shall divide the total toys assembled by the total hours.
Its a five day week.
The number of hours allotted per day are 8.
So total allotted during the week are 8 × 5 = 40 hours.
Number of toys made during the week are 400.
Hence the number of toys assembled per hour per person
= number of toys / number of hours
= 400 / 40
= 10 toys per hour per person.
The average number of toys assembled per hour per person is 10.