Question

seven pipes are required to fill a tank in 1 hours 30 minutes how long will it take if only 6 pipes of the same type are used

Answer 1

convert 1 hr 30 mins into minutes.= 90 mins
seven pipes take 90 mins
so one pipe will take 90 ÷ 7 mins
and 6 pipes take(90÷7)* 6 mins