# Math Help - mcq about algebra

1. ## mcq about algebra

Q15: Jamil can fill a pool carrying buckets of water in 30 minutes. Ali can do
the same job in 45 minutes. Tariq can do the same job in 1 ½ hours.
How quickly can all three fill the pool together?
A. 12 minutes
B. 15 minutes
C. 21 minutes
D. 23 minutes

how??

2. Set these up as ratios of minutes : proportion of pool filled...

Jamil $\displaystyle 30 : 1 \implies 1 : \frac{1}{30}$

Ali $\displaystyle 45 : 1 \implies 1 : \frac{1}{45}$

Tariq $\displaystyle 90 : 1 \implies 1 : \frac{1}{90}$.

So that means, if they did it together, every minute they would fill $\displaystyle \frac{1}{30} + \frac{1}{45} + \frac{1}{90} = \frac{3}{90} + \frac{2}{90} + \frac{1}{90} = \frac{6}{90} = \frac{1}{15}$ of the pool. Therefore they would fill it in 15 minutes.