# RRB NTPC - Time and Work :(96) MCQs with Answers

1.

A and B working together can complete a work in 12 days, B and C working together will complete the work in 15 days, C and A working together can complete the work in 20 days. If all three work together, in how many days the work can be completed?

A.) 10 days
B.) 8 days
C.) 13 days
D.) 12 days

Given
A + B 's one day work will be 1/12
Similarly, B + C's one day work will be 1/15
C + A 's one day work be 1/20
A + B = 1/12 ----> (1)
B + C = 1/15 ----> (2)
C + A = 1/20 ----> (3)
Adding all the above equation we get
2(A+B+C) = 1/12 + 1/15 + 1/20
=> 5/60 + 4/60 + 3/60
=> 12/60
A+B+C = 12 / 120
= 1/10
If all three work together, the work will be completed in 10 days.

2.

A can finish a work in 18 days and B can do the same work in half the time taken by A. Then, working together, what part of the same work they can finish in a day?

A.) 1/6
B.) 1/9
C.) 2/5
D.) 2/7

B alone can do the same work in 9 days
So, the No. of days both of them together take to do the work = 18 × 9/ 18 + 9
=18 × 9/27 = 6 days.
The part of the work, they together finish in one day = 1/6.

3.

Three men, four women and six children can complete a work in 7 days . A woman does double the work a man does and a child does half the work a man does. How many women can complete this work in 7 days?

A.) 8
B.) 7
C.) 12
D.) 14

3 men = 3/2 women
1 child = 1/2/2 = ¼ woman
Then, 6 children = ¼ × 6 = 6/4 = 3/2 women
Then, 3/2 women + 4 women + 3/2 women = 7 women
7 women does the work in 7 days.
Therefore, the No. of women required to finish the work in 7days = 7.

4.

A can do a work in 4 days, B can do it in 5 days and C can do it in 10 days. A, B and C together can do the work in

A.) 1 3/5 days
B.) 1 9/11 days
C.) 2 5/6 days
D.) 3 days

When A, B and C can do a work in x, y and z days respectively. Then, the three of them
together can finish the work in xyz/ x y + y z + x z days
That is, A, B and C together ca do the work in 4 × 5 × 10/ 20 + 50 + 40
= 4 × 5 × 10/110 = 20/11 = 1 9/11 days.

5.

Six men or tern boys can do a piece of work in fifteen days. How long would it take for 12 men and 5 boys to do the same piece of work?

A.) 6 days
B.) 28 days
C.) 25 days
D.) 7 days

6 men = 10 boys
Then, 1 boy = 6/10 men = 3/5 men
Then, 5 boys = 3/5 × 5 = 3 men
12 men + 5 boys = 15 men
1 work done = 6 men × 15 days
Therefore, 6 × 15 = 15 × ? days
? days = 6 × 15/15 = 6 days.