10
Q:

A group of workers was put on a job. From the second day onwards, one worker was withdrawn each day. The job was finished when the last worker was withdrawn. Had no worker been withdrawn at any stage, the group would have finished the job in 55% of the time. How many workers were there in the group?

A) 50 B) 40
C) 45 D) 10

Answer:   D) 10

Explanation:

It can be solved easily through option.

        \inline \left ( 10+9+8+....+1 \right )=10\left ( 10\times \frac{55}{100} \right )

                     55 = 55     Hence correct

 

Alternatively:

        \inline \frac{n(n+1)}{2}=n\times \frac{55n}{100}

         => n= 10

In Both cases total work is 55man-days.

Q:

A,B,C together can do a piece of work in 10 days.All the three started workingat it together and after 4 days,A left.Then,B and C together completed the work in 10 more days.In how many days can complete a work alone ?

A) 25 B) 24
C) 23 D) 21
 
Answer & Explanation Answer: A) 25

Explanation:

(A+B+C) do 1 work in 10 days.
So (A+B+C)'s 1 day work=1/10 and as they work together for 4 days so workdone by them in 4 days=4/10=2/5
Remaining work=1-2/5=3/5
(B+C) take 10 more days to complete 3/5 work.
So( B+C)'s 1 day work=3/50
Now A'S 1 day work=(A+B+C)'s 1 day work-(B+C)'s 1 day work=1/10-3/50=1/25
A does 1/25 work in in 1 day
Therefore 1 work in 25 days.

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1 6
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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1 12
Q:

There is sufficient salary to give K for 10 days and L for 15 days. Then how many days will the money last if both has to be given the salary ?

A) 6 days B) 12 days
C) 4 days D) 9 days
 
Answer & Explanation Answer: A) 6 days

Explanation:

K's 1 day's salary = 1/10
L's 1 day's salary = 1/15
Together their 1 day's salary = 1/10 + 1/15
= 3/30 + 2/30
= 5/30
= 1/6
So the money will be
enough for paying them both for 6 days.

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1 12
Q:

4 men can repair a road in 7 hours. How many men are required to repair the road in 2 hours ?

A) 17 men B) 14 men
C) 13 men D) 16 men
 
Answer & Explanation Answer: B) 14 men

Explanation:

M x T / W = Constant
where, M= Men (no. of men)
T= Time taken
W= Work load
So, here we apply
M1 x T1/ W1 = M2 x T2 / W2
Given that, M1 = 4 men, T1 = 7 hours ; T2 = 2 hours, we have to find M2 =?
Note that here, W1 = W2 = 1 road, ie. equal work load.
Clearly, substituting in the above equation we get, M2 = 14 men.

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2 30
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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