Question Detail

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

5 days
6 days
7 days
8 days

Answer: Option B

Explanation:

Firstly we will find 1 day work of both A and B, then by adding we can get collective days for them,
So,
A's 1 day work = 1/10
B's 1 day work = 1/15

(A+B)'s 1 day work =

$\begin{aligned} \left(\frac{1}{10}+\frac{1}{15} \right) \\ =\left(\frac{3+2}{30} \right) \\ = \frac{1}{6} \end{aligned}$

So together they can complete work in 6 days.

1. A completes 80% of a work in 20 days. Then B also joins and A and B together finish the remaining work in 3 days. How long does it need for B if he alone completes the work?

$\begin{aligned} 35\frac{1}{2} \end{aligned}$
$\begin{aligned} 36\frac{1}{2} \end{aligned}$
$\begin{aligned} 37\frac{1}{2} \end{aligned}$
$\begin{aligned} 38\frac{1}{2} \end{aligned}$

Answer: Option C

Explanation:

Work done by A in 20 days = 80/100 = 8/10 = 4/5

Work done by A in 1 day = (4/5) / 20 = 4/100 = 1/25 --- (1)

Work done by A and B in 3 days = 20/100 = 1/5 (Because remaining 20% is done in 3 days by A and B)

Work done by A and B in 1 day = 1/15 ---(2)

Work done by B in 1 day = 1/15 – 1/25 = 2/75

=> B can complete the work in 75/2 days = 37 (1/2) days

2. A alone can complete a work in 16 days and B alone can do in 12 days. Starting with A, they work on alternate days. The total work will be completed in

$\begin{aligned} 13\frac{1}{4} \end{aligned}$
$\begin{aligned} 13\frac{1}{2} \end{aligned}$
$\begin{aligned} 13\frac{3}{4} \end{aligned}$
$\begin{aligned} 13\frac{4}{4} \end{aligned}$

Answer: Option C

Explanation:

A's 1 day work = 1/16
B's 1 day work = 1/12

As they are working on alternate day's
So their 2 days work = (1/16)+(1/12)
= 7/48

[here is a small technique, Total work done will be 1, right, then multiply numerator till denominator, as 7*6 = 42, 7*7 = 49, as 7*7 is more than 48, so we will consider 7*6, means 6 pairs ]

Work done in 6 pairs = 6*(7/48) = 7/8

Remaining work = 1-7/8 = 1/8

On 13th day it will A turn,
then remaining work = (1/8)-(1/16) = 1/16

On 14th day it is B turn,

1/12 work done by B in 1 day

1/16 work will be done in (12*1/16) = 3/4 day

So total days =

$\begin{aligned} 13\frac{3}{4} \end{aligned}$

It may be a bit typical question, but if are not getting it in first try then give it a second try. Even not, then comment for explanation for this. We will be happy to help you.

3. Worker A takes 8 hours to do a job. Worker B takes 10 hours to do a job. How long should it take both A and B, working together to do same job.

$\begin{aligned} \frac{4}{9} \end{aligned}$
$\begin{aligned} 2\frac{4}{9} \end{aligned}$
$\begin{aligned} 3\frac{4}{9} \end{aligned}$
$\begin{aligned} 4\frac{4}{9} \end{aligned}$

Answer: Option D

Explanation:

In this type of questions, first we need to calculate 1 hours work, then their collective work as,

A's 1 hour work is 1/8
B's 1 hour work is 1/10

(A+B)'s 1 hour work = 1/8 + 1/10
= 9/40

So both will finish the work in 40/9 hours
=

$\begin{aligned} 4\frac{4}{9} \end{aligned}$

4. A is twice as good as workman as B and together they finish a piece of work in 18 days. In how many days will B alone finish the work.

27 days
54 days
56 days
68 days

Answer: Option B

Explanation:

As per question, A do twice the work as done by B.
So A:B = 2:1
Also (A+B) one day work = 1/18

To get days in which B will finish the work, lets calculate work done by B in 1 day =

$\begin{aligned} =\left(\frac{1}{18}*\frac{1}{3} \right) \\ = \frac{1}{54} \end{aligned}$
[Please note we multiplied by 1/3 as per B share and total of ratio is 1/3]

So B will finish the work in 54 days

5. A can do a certain job in 25 days which B alone can do in 20 days. A started the work and was joined by B after 10 days. The number of days taken in completing the wotk were ?

$\begin{aligned} 14\frac{2}{3}kmph \end{aligned}$
$\begin{aligned} 15\frac{2}{3}kmph \end{aligned}$
$\begin{aligned} 16\frac{2}{3}kmph \end{aligned}$
$\begin{aligned} 17\frac{2}{3}kmph \end{aligned}$

Answer: Option C

Explanation:

Work done by A in l0 days = (1/25) *10 = 2/5
Remaining work = 1 - (2/5) = 3/5
(A+B)s 1 days work = (1/25) + (1/20) = 9/100

9/100 work is done by them in 1 day.
hence 3/5 work will be done by them in (3/5)*(100/9)
= 20/3days.

Total time taken = (10 + 20/3) = 16*(2/3) days

Sujith 8 years ago

one pump can fill a tank in 4 hrs another will vacate in 5 hrs. In what time will the tank be filled when both the pumps work simultaneously?

Question Detail

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

1. A completes 80% of a work in 20 days. Then B also joins and A and B together finish the remaining work in 3 days. How long does it need for B if he alone completes the work?

2. A alone can complete a work in 16 days and B alone can do in 12 days. Starting with A, they work on alternate days. The total work will be completed in

3. Worker A takes 8 hours to do a job. Worker B takes 10 hours to do a job. How long should it take both A and B, working together to do same job.

4. A is twice as good as workman as B and together they finish a piece of work in 18 days. In how many days will B alone finish the work.

5. A can do a certain job in 25 days which B alone can do in 20 days. A started the work and was joined by B after 10 days. The number of days taken in completing the wotk were ?

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Sujith 8 years ago

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Question Detail

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

1. A completes 80% of a work in 20 days. Then B also joins and A and B together finish the remaining work in 3 days. How long does it need for B if he alone completes the work?

2. A alone can complete a work in 16 days and B alone can do in 12 days. Starting with A, they work on alternate days. The total work will be completed in

3. Worker A takes 8 hours to do a job. Worker B takes 10 hours to do a job. How long should it take both A and B, working together to do same job.

4. A is twice as good as workman as B and together they finish a piece of work in 18 days. In how many days will B alone finish the work.

5. A can do a certain job in 25 days which B alone can do in 20 days. A started the work and was joined by B after 10 days. The number of days taken in completing the wotk were ?

Thanks ! Your comment will be approved shortly !

Sujith 8 years ago

Videos @mastguru

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