46.

A and B can together finish a work in 30 days. they worked at it for 20 days and then B left. the remaining work ws done by A alone in 20 more days. A alone can finish the work in :

 A. 48 Days B. 50 days C. 54 Days D. 60 days
Answer:D
Explanation:

47.

A and B can do a piece of work in 45 days and 40 days respectively. They began to do the work together but A leaves after some days and then B completed the remaining work in 23 days. The number of days after which A left the work was

 A. 12 B. 11 C. 10 D. 9
Answer:D
Explanation: (A+B)’s 1 day’s work =[ 1 45 + 1 40 ]= 17 360 ⇒ Work done by B in 23 days=1× 23 40 = 23 40 ⇒ Remaining work =1− 23 40 = 17 40 ⇒ Now, 17 360 work was done by (A+B) in 1 day. ⇒ 17 40 work was done by (A+B) in 1× 360 17 × 17 40 =9 days. Therefore, A left after 9 days.

48.

A and B can do a piece of work in 45 days and 40 days respectively. They began to do the work together but A leaves after some days and then B completed the remaining work in 23 days. The number of days after which A left the work was

 A. 12 B. 11 C. 10 D. 9
Answer:D
Explanation: (A+B)’s 1 day’s work =[ 1 45 + 1 40 ]= 17 360 ⇒ Work done by B in 23 days=1× 23 40 = 23 40 ⇒ Remaining work =1− 23 40 = 17 40 ⇒ Now, 17 360 work was done by (A+B) in 1 day. ⇒ 17 40 work was done by (A+B) in 1× 360 17 × 17 40 =9 days. Therefore, A left after 9 days.

49.

Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank in gallons is

 A. 100 B. 110 C. 120 D. 140
Answer:C
Explanation: Work done by the waste pipe in 1 minute ⇒ 1 15 –[ 1 20 + 1 24 ] ⇒ 1 15 − 11 120 =− 1 40 ⇒volume of 1 40 part = 3 gallons. Therefore, Volume of whole =(3×40)gallons = 120 gallons.

50.

39 persons can repair a road in 12 days, working 5 hours a day. In how many days will 30 persons, working 6 hours a day, complete the work?

 A. 10 B. 13 C. 14 D. 15
Answer:B
Explanation: Let's calculate how much time it takes to repair the road if just 1 person were working on it. 5 hours a day for 12 days makes it 60 hours per person. 39 people working 60 hours each makes it 39×60=2340 hours in total. Now we have 30 people working 6 hours a day ⇒ That means 30×6=180 hours are spent each day. We need a total of 2340 hours. With 180 hours every day, that's going to take 2340 180 = 13 days to complete... Or you could just do it in one step... :) 39×12×5=30×x×6 2340=180x x= 2340 180 x = 13.