Time and Work Questions

Q:

A does half as much work as Band C does half as much work as A and B together. If C alone can finish the work in 40 days, then together ,all will finish the work in  ?

A) 17 + 4/7 days B) 13 + 1/3 days
C) 15 + 3/2 days D) 16 days
 
Answer & Explanation Answer: B) 13 + 1/3 days

Explanation:

C alone can finish the work in 40 days.
As given C does half as much work as A and B together
=> (A + B) can do it in 20 days
(A + B)s 1 days wok = 1/20.
A's 1 days work : B's 1 days Work = 1/2 : 1 = 1:2(given)
A's 1 day’s work = (1/20) x (1/3) = (1/60) [Divide 1/20 in the raio 1:2]
B's 1 days work = (1/20) x (2/3) = 1/30
(A+B+C)'s 1 day's work = (1/60) + (1/30) + (1/40) = 9/120 = 3/40

All the three together will finish it in 40/3 = 13 and 1/3 days.

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Q:

If 6 engines consume 24 metric tonnes of coal, when each is working 8 hours day, how much coal will be required for 9 engines, each running 13hours a day, it being given that 2 engines of former type consume as much as 3 engines of latter type ?

A) 45 metric tonnes B) 47 metric tonnes
C) 55 metric tonnes D) 34 metric tonnes
 
Answer & Explanation Answer: A) 45 metric tonnes

Explanation:

2 engines of former type for one hour consumes 2x24/(6x8) = 1 metric ton
i.e. 3 engines of latter type consumes 1 ton for one hour
hence 9 engines consumes 3 tons for one hour
for 15 hours it is 15 x 3 = 45 metric tonnes.

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Q:

K can finish the work in 18 days and L can do the same work in 15 days. L worked for 10 days and left the job. In how many days, K alone can finish the remaining work ?

A) 5.5 days B) 6 days
C) 4.2 days D) 5 days
 
Answer & Explanation Answer: B) 6 days

Explanation:

L's 10 days work = 
Remaining work = 
Now,  work is done by K in one day
 work is done by K in 

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Q:

9 men and 12 boys finish a job in 12 days, 12 men and 12 boys finish it in 10 days. 10 men and 10 boys shall finish it in how many days ?

A) 15 days B) 11 days
C) 14 days D) 12 days
 
Answer & Explanation Answer: D) 12 days

Explanation:

9M + 12B ----- 12 days ...........(1)
12M + 12B ------- 10 days........(2)
10M + 10B -------?
108M + 144B = 120M +120B
24B = 12M => 1M = 2B............(3)

From (1) & (3)

18B + 12B = 30B ---- 12 days

20B + 10B = 30B -----? => 12 days.

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Q:

A can write 32 pages in 6 hours and B can write 40 pages in 5 hours. If they write together, in how many hours they can write 110 pages ?

A) 7 hrs B) 6 hrs 10 min
C) 5 hrs 25min D) 8 hrs 15 min
 
Answer & Explanation Answer: D) 8 hrs 15 min

Explanation:

A can write in 1hour = 32/6 pages
similarly
B in 1 hour = 40/5 pages

Together (A+B) in 1 hour = 32/6 + 40/5 = 40/3
so,
A+B write 40/3 pages in 1 hour
A+B write 110 pages in (3/40) x 110 Hours = 8 hours 15 min.

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