Q 1-A and B can do a work in 12 days, B and C in 15 days,. C and A in 20 days . If A, B and C work together they will complete the work in :

A - 5 days

B - 10 days

C - 15 days

D - 20 days

Answer - B Explanation "(A + B)'s 1 day's work = 1/12 ; (B + C)'s 1 day's work = 1/15 , (A + C)'s 1 day's work = 1/20 Adding, we get : 2(A + B + C)'s 1 day work = ( [1/12]+[1/15]+[1/20] ) = 12/60 = 1/5 (A + B + C)'s 1 day's work = 1/10 So, A, B and C together can complete the work in 10 days. "

Q 2-P can complete a work in 12 days working 8 hours a day Q can complete the same work in 8 days working 10 hours a day . If both P and Q work together ,working 8 hours a day in how many days can hey complete the work ?

A - 5(5/11)

B - 5(6/11)

C - 6(5/11)

D - 6(6/11)

Answer - A Explanation "P can complete the work in (12 x 8) hrs. = 96 hrs. Q can complete the work in ( 8 x 10) hrs. = 80 hrs. ∴p's 1 hour's work = 1/96 and Q's 1 hour's work = 1/80 (P + Q )'s 1 hours work = ( [1/96]+[1/80] ) = 11/480 So, both P and Q will finish the work in (480/11) hrs. ∴Number of days of 8 hours each = ( [480/11]× [1/8] ) =60/11 days = 5(5/11) days. "

Q 3-Two workers A and B are engaged to do a work. A working alone takes 8 hours more to complete the job than if both worked together . If B worked alone he would need 4(1/2) hours more to complete he job than both working together . What time would they take to do the work together ?

A - 4 hours.

B - 5 hours

C - 6 hours

D - 7 hours.

Answer - C Explanation "Let A and B together take x hours to complete the work . then, A alone takes (x+8) hrs and B alone takes (x+[9/2] ) hrs to complete the work . Then , [1/(x+8) ]+[1/(x+{9/2}) ] =1/ x ⇒ [1/(x+8)]+[ 2/(2x+9) ] = 1/x ⇒ x(4x+25)=(x+8)(2x+9) ⇒ 2x² =72 ⇒ x² = 36 ⇒ x=6. "

Q 4-Ronald and Elan are working on an assignment . Ronald takes 6 hours to type 32 pages on a computer, while takes 5 hours to type 40 pages. How much time will hey take working together on two different computers to type an assignment of 110 pages?

A - 7 hours 30 minutes

B - 8 hours

C - 8 hours 15 minutes

D - 8 hours 25 minutes.

Answer - C Explanation "Number of pages typed by Ronald in 1 hour = 3/26 = 16/3 Number of pages typed by Elan in 1 hour = 40/5 = 8. Number of pages typed by both in 1 hour = ( [16/3]+8) =40/3 ∴Time taken by both to type 110 pages = (110×[3/40] )hrs. = 8(1/4)hrs. = 8 hrs. 15 min. "

Q 5-P, Q and R are three typists who working simultaneously can type 216 pages in 4 hours . In one your, R can many pages more than Q as Q can type more than P . During a period of five hours, R can type as many pages as P can seven hours. How many pages does each of them type per hour ?

A - 14, 17, 20

B - 15, 17, 22

C - 15, 18, 21

D - 16, 18, 22

Answer - C Explanation "Let the number of pages typed in one hour by P, Q and R be x,y and z respectively. Then. x+y+z=216/4 ⇒x+y+z= 54.........................(I) z−y = y−x ⇒ 2y =x+z.............................(II) 5z=7x ⇒ x=(5/7)z.............................(III) Solving (I),(II) and (III) , we get x = 15, y=18, z= 21. "

Q 6-X can do 1/4 of a work in 10 days. Y can do 40% of the work in 40 days and Z can do 1/3 of the work in 13 days. Who will complete the work first ?

A - X

B - Y

C - Z

D - X and Z both

Answer - C Explanation "Whole work will be done by X in (10 x 4) = 40 days Whole work will be done by Y in (40×[100/40] ) = 100 days Whole work will be done by Z in (13 x 3) = 39 days. ∴Z will complete the work first . "

Q 7-A takes twice as much time as B or thrice as much time to finish a piece of work . working together .they can finish the work in 2 days. B can do the work alone in .

A - 4 days

B - 6 days

C - 8 days

D - 12 days

Answer - B Explanation "Suppose A, B and C take x,(x/2) and x/3 hours. respectively to finish the work. Then , ( [1/2]+[2/x]+[3/x] ) =1/2 ⇒ 6/x = 1/2 ⇒ x=12 So, B takes 6 days to finish the work "

Q 8-A can lay railway track between two given stations in 16 days and B can do the same job in 12 days . With the help if C, they did the job in 4 days only . hen , C alone can do the job in .

A - 9(1/2) days

B - 9(2/5)days

C - 9(3/5)days

D - 10 days

Answer - C Explanation "(A + B + C)'s 1 day's work = 1/4, A's 1 day's work = 1/16, B's 1 day's work = 1/12 ∴C's 1 day's work = 1/4−( [1/16]+[1/12] ) = ( [1/4]− [7/48] ) =5/48. So, C alone can do the work in 48/5 =9(3/5) days. "

Q 9-A man can do a piece of work in 5 days, but with the help of his son, he can do it is 3 days. In what time can the son do it alone ?

A - 6 days

B - 7 days

C - 7(1/2)

D - 8 days

Answer - C Explanation "Son's 1 day's work = ([1/3]−[1/5]) = 2/15 ∴The son alone can do the work in 15/2 =7(1/2)days "

Q 10-A man can do a job in 15 days. His father takes 20 days and his son finishes it in 25 days. How long will they take to complete the job if they all work together ?

A - Less than 6 days

B - Ezactly 6 days.

C - Approximately 6.4 days

D - More than 10 days

Answer - C Explanation "1 day's work of the three persons = ( [1/15]+[1/20] +[1/25] ) =47/300 So, all the three together will complete the work in 300/47 = 6.4 days "

Q 11-A, B and C can complete a piece of work in 24, 6 and 12 days respectively. Working together, they will complete the same work in :

A - 1/2 days

B - 2 days

C - 3(1/7) days

D - 4 days

Answer - C Explanation "(A + B + C)'s 1 day's work = ( [1/24]+[1/6]+[1/12] ) =7/24. So, A, B and C together will complete the job in 24/7 = 3(3/7) days. "

Q 12-A type has two punctures. The first puncture alone would have made the tyre flat in 9 minutes and the second alone would have done it in 6 minutes . If air leaks out at 1 constant rate . how long does it take both the punctures together to make it flat ?

A - 1(1/2) minutes

B - 4(1/4)minutes

C - 3(1/2)minutes

D - 3(3/5)minutes

Answer - D Explanation "1 minute's work of both the punctures = ( [1/9]+[1/6] ) =5/18 So, both the punctures will make the tyre flat in 18/5 = 3(3/5) minutes. "

Q 13-A can finish a work in 18 days and B can do the same work in half the time takes by A. Then , working together.what par of the same work hey an finish in a day.

A - 1/6

B - 1/9

C - 2/5

D - 2/7

Answer - A Explanation "A's 1 day's work = 1/18 and B's 1 day's work = 1/9 ∴(A + B)'s 1 day's work = ( [1/18]+[19] ) = 1/6 "

Q 14-A does a work in 10 days and B does he same work in 15 day . In how many days they together will do the same work ?

A - 5 days

B - 6 days

C - 8 days

D - 9 days

Answer - B Explanation "A's 1 day's work = 1/10 and B's 1 day's work = 1/15 ∴(A + B)'s 1 day's work = ( [1/10]+[1/15] ) = 1/6 So , both together will finish the work in 6 days. "

Q 15-2 men and 3 boys can do a piece of work in 10 days while 3 men and 2 boy can do the same work in 8 days. In how many days can 2 men and 1 boy do the work ?

A - 12(1/2) days

B - 13 days

C - 13(1/2) days

D - 14 days

Answer - A Explanation "Let 1 men's work 1 day work = x and 1 boy's 1 day's work = y Then . 2x + 3y= 1/10 and 3x + 2y = 1/8 Solving . we get : x = 7/200 and y=1/100 ∴(2 men + 1 boys) 1 day's work = (2×[7/200]+1×[1/100] ) = 16/200 = 2/25 so, 2 men and 1 boy together can finish the work in 25/2 =12(1/2) days. "