Question

pipe a and b can fill an empty tank in 10 and12 hours respectively.If both pipes open together then how much time it takes to fill the tank

Answer 1

pipe a in 1 hour =1÷10
pipe b in 2 hour = 1÷12
$\frac{1}{10} + \frac{1}{12}$
$\frac{6}{60} + \frac{5}{60}$
$\frac{11}{60}$
hours=60÷11

$5 \times \frac{5}{11}$