Question

Two pipes a and b can fill a tank in 12 or 24 minutes if both pipes are used together how much used to fill

Answer 1

1/12+1/24=1/8

therefore answer is 8minutes

Answer 2

pipe a can fill tank in 12 minutes

so pipea will fill tank in 1 minute = 1/12

pipe b can fill tank in 24 mins

pipe b will fill tank in 1 min = 1/24

pipe a and b together will fill tank in 1 min =

$\frac{1}{12} + \frac{1}{24} \\ ( \frac{1}{24} ) \times (2 + 1) \\ \frac{3}{24} \\ \frac{1}{8}$

1/ 8 tank filled in 1 minute

tank will be filled in

$\frac{1}{ \frac{1}{8} } \\ 8 \: mins$

8 mins