Question

you estimate that you can do 30 math problems in 45 minutes. How many minutes should it take you to do 40 math problems?

Answer 1

60 minutes

Explanation:

Proportions:

Number of problems done, and the time taken to finish them are in proportion.

Let the time taken to finish 40 problems = 'x'

30 : 45 = 40 : x

Product of extremes = 30 *x = 30x

Product of means = 45 * 40

Product of extremes = Product of means

30 *x = 45 * 40

`\sf x = (45*40)/(30)`

x = 15 * 4

x = 60 minutes