Question

A printer, prints a book of 300 pages at the rate of 30 pages per minute. Then, how long will it take to print the same book if the speed of the printer is 25 pages per minute?

Answer 1

Let the required time taken to print be x

As the speed increases time taken to print decreases

∴ They are in inverse proportion

Time taken to print 30 pages = 1 min

∴ Time taken to print 300 pages = `300/30` = 10 min

Time taken to print (in minutes)	10	x
Number of pages printed per minutes	30	25

x₁y₁ = x₂y₂

10 × 30 = x × 25

x = `(30 xx 10)/25` = 12 min

Time taken to print = 12 min