ANSWER : 10

Explanation : : Due to stoppages,it cover 9 kms less Time taken to cover 9 km=(9/54 x 60)minutes =10 minutes

ANSWER : 15

Explanation : : Chain rule method, 30 x 6 x 12/ 750 =24 x 9 x X / 1125 x =30 x 6 x12 x 1125 / 750 x 24 x 9 =15 days

ANSWER : 23 1/3 minutes

Explanation : : Pipe can filled in 1 minute=1/40 part of the drum Pipe can empty in 1 minute=1/60 part of the drum Second pipe opened in 15 minutes tank empty by=15/60 part of the drum =1/4 part of the drum Remaining oil part of the drum =2/3-1/4=8-3/12 =5/12 The empty space=1-5/12=7/12 1/40 part of drum filled in, 7/12 / 1/40=70/3 =23 1/3 minutes

ANSWER : 12

Explanation : : Chain rule method, 40 x X / 1=30(x+6)/1 40x=30x+30+6 10x=180 x=180/10=18 days Now, 60 x y/1 =40 x18 / 1 y=40 x 18 /60 =12 days 60 men can do the work in 12 days

ANSWER : 90 days

Explanation : : (A+B)'s 1 day work =1/36 If A works alone the last 10 days,it is completed in 40 days (A+B) worked jointly in 30 days A alone works in 10 days (A+B)'s 30 days work=30/36 Remaining work=6/36 part of work done by A in 10 days Whole work done by A=10 x 36/6=60 days A's 1 day work =1/60 B alone can do the work=(A+B)'s 1 day work-A's 1 day work =1/36-1/60 =24/36 x 60=90 days