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Question: 6 Adults can do a job twice as faster as children. If X adults can complete a job in a day, how many children can do the same job in (d + 2) days?
Option: (a) 2dx/(d +2) (b) (d + 2)x/d (c) dx/2(d + x) (d) (2x + d)/(d - x) (e) None of these
Explore:
X adults can do the job in d days
:. 2X children can do the job in d days
:. 2xd children can do the job in d days
:. (2xd)/(d + 2) children can do the job in (d + 2) days
Answer : (a)
Question: 7 Mr. X can finish a work in 6 days and Mr. Ly can finish the same work in 8 days. How long will it take to finish the work together?
Explore:
Mr. X in 6 days can finish 1 portion
:. Mr. X in 1 days can finish 1/6 portion
Mr. y in 8 days can finish 1 portion
:. Mr. y in 1 days can finish 1/8 portion
:. In 1 day X & Y can finish (1/6 + 1/8) Portion
= (4 + 3)/24
= 7/24
:. X & Y together finish 7/24 portion in 1 day
:. X & Y together finish 1 portion in (1 x 24)/7
= 24/7
= 3(3/7) days
Answer : 3(3/7) days
Question: 8 A can dig a pond in 30 days and B can dig the same pond in 20 days. In how many days A and B can dig the pond if they work together?
Explore:
A in 30 days can dig 1 portion
:. A in 1 days can dig 1/30 portion
B in 20 days can dig 1 portion
:. B in 1 days can dig 1/20 portion
A & B together in 1 day can dig (1/30 + 1/20) portions
= (2 + 3)/60 portion
= 5/60 portion
= 1/12 Portion
A & B together can dig 1/12 portion in 1 day
:. A & B together can dig 1 portion in (1 x 13)/1 day
= 12 day
Answer : A & B together can dig in 12 days.
Question: 9 Jim can fill a pool carrying bucks of water in 30 minutes. Sue can do the same job in 45 minutes. Tony can do the same job in 1(1/2) hours. How quickly can all the three fill the poll together?
Option: (a) 12 minutes (b) 15 minutes (c) 21 minutes (d) 23 minutes (e) 28 minutes
Explore:
1(1/2) hours = 60 + 30 Minutes
= 90 minutes
Jim in 30 minutes can do 1 portion
:. Jim in 1 minutes can do 1/30 portion
Similarly,
Sue in 1 minutes can do 1/45 portion
& Tony in 1 minutes can do 1/ 90 portion
Together all the three in 1 minute can do (1/30 + 1/45 + 1/90) portion
= (3+2+1)/90
= 6/90
= 1/15
Together 1/15 portion is finished in 1 minute
:. Together 1 portion is finished in (1 x 15)/1 minutes
= 15 minutes
Answer : (b)
Question: 10 A and B can do a work in 12 days. B and C can do it in 15 days. and A and C can do it in 20 days. If all of them work together, in how many days they can finish the work?
Option: (a) 25 (b) 9 (c) 12 (d) 10 (e) 22
Explore:
A & B in 12 days can do 1 portion
:. A & B in 1 days can do 1/12 portion
B & C in 15 days can do 1 portion
:. B & C in 1 days can do 1/15 portion
A & C in 20 days can do 1 portion
:. A & C in 1 days can do 1/20 portion
:. 2A, 2B and 2C in 1 day can do (1/12 + 1/15 + 1/20) portion
= (5 + 4 + 3)/60
= 12/60
= 1/5 portion
:. 2A, 2B & 2C can finish 1/5 portion in 1 day
:. 2A, 2B & 2C can finish 1 portion in (1 x 5)/1 day
:. A, B & C can finish 1 portion in (5 x 2) = 10 days
Answer : (d)
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