Question Detail

A and B can together complete a piece of work in 4 days. If A alone can complete the same work in 12 days, in how many days can B alone complete that work ?

4 days
5 days
6 days
7 days

Answer: Option C

Explanation:

(A+B)'s 1 day work = 1/4

A's 1 day work = 1/12

B's 1 day work =

$\begin{aligned} \left( \frac{1}{4} - \frac{1}{12} \right) \\ = \frac{3-1}{12} \\ = \frac{1}{6} \\ \end{aligned}$

So B alone can complete the work in 6 days

1. 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.

2. Rahul and Sham together can complete a task in 35 days, but Rahul alone can complete same work in 60 days. Calculate in how many days Sham can complete this work ?

84 days
82 days
76 days
68 days

Answer: Option A

Explanation:

As Rahul and Sham together can finish work in 35 days.
1 days work of Rahul and Sham is 1/35
Rahul can alone complete this work in 60 days,
So, Rahul one day work is 1/60
Clearly, Sham one day work will be = (Rahul and Sham one day work) - (Rahul one day work)

$\begin{aligned} = \frac{1}{35} - \frac{1}{60} \\ = \frac{1}{84} \\ \end{aligned}$

Hence Sham will complete the given work in 84 days.

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

$\begin{aligned} 7\frac{1}{2}days \end{aligned}$
$\begin{aligned} 6\frac{1}{2}days \end{aligned}$
$\begin{aligned} 5\frac{1}{2}days \end{aligned}$
$\begin{aligned} 4\frac{1}{2}days \end{aligned}$

Answer: Option A

Explanation:

In this type of question, where we have one person work and together work done. Then we can easily get the other person work just by subtracting them. As,

Son's one day work =

$\begin{aligned} \left(\frac{1}{3}-\frac{1}{5} \right) \\ =\left(\frac{5-3}{15} \right) \\ = \frac{2}{15} \end{aligned}$

So son will do whole work in 15/2 days
which is =

$\begin{aligned} 7\frac{1}{2}days \end{aligned}$

5. A can do a piece of work in 4 hours . A and C together can do it in just 2 hours, while B and C together need 3 hours to finish the same work. In how many hours B can complete the work ?

10 hours
12 hours
16 hours
18 hours

Answer: Option B

Explanation:

Work done by A in 1 hour = 1/4

Work done by B and C in 1 hour = 1/3

Work done by A and C in 1 hour = 1/2

Work done by A,B and C in 1 hour = (1/4)+(1/3) = 7/12

Work done by B in 1 hour = (7/12)–(1/2) = 1/12

=> B alone can complete the work in 12 hour

Question Detail

A and B can together complete a piece of work in 4 days. If A alone can complete the same work in 12 days, in how many days can B alone complete that work ?

1. 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 ?

2. Rahul and Sham together can complete a task in 35 days, but Rahul alone can complete same work in 60 days. Calculate in how many days Sham can complete this work ?

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

5. A can do a piece of work in 4 hours . A and C together can do it in just 2 hours, while B and C together need 3 hours to finish the same work. In how many hours B can complete the work ?

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Question Detail

A and B can together complete a piece of work in 4 days. If A alone can complete the same work in 12 days, in how many days can B alone complete that work ?

1. 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 ?

2. Rahul and Sham together can complete a task in 35 days, but Rahul alone can complete same work in 60 days. Calculate in how many days Sham can complete this work ?

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

5. A can do a piece of work in 4 hours . A and C together can do it in just 2 hours, while B and C together need 3 hours to finish the same work. In how many hours B can complete the work ?

Thanks ! Your comment will be approved shortly !

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