Question

90% of runners who started a marathon completed it. Of those, 30% are men. If 270 men completed the marathon, then how many total runners started the marathon?

Answer 1

Given- 90% of runner completed the marathon.

out of which 30% are man.

To proof -  let the total number of runner be y.

the men completed the marathon be 30% of the 90%.

thus we have

30% of 90% of y = 270

$\frac{30}{100}$×$\frac{90}{100}$×y = 270

now solving the above equation

we get

$\\y=\frac{270\times 100\times 100}{90\times 30}$

Thus solving the equation

y = 1000

Thus the total runners of men who completed marathon be 1000.

Hence proved