Time and work Quantitative aptitude question

[Q] A and B are working on an assignment. A takes 6 hours to type 32 pages on a computer, while B takes 5 hours to type 40 pages. How much time will A and B take, working together on two different computers to type an assignment of 110 pages?
(a) 10 hour 15 minutes
(b) 7 hour 15 minutes
(c) 8 hour 15 minutes
(d) 9 hour 15 minutes

Solution

Answer   (c)
Explanation
----
Pages typed by A in 1 hour = 32/6 = 16/3

Pages typed by B in 1 hour = 40/5 = 8

Pages typed by A and B in 1 hour = 16/3 + 8 = 40/3

Time taken to type 110 pages when A and B work together = 110 × 3 /40 = 33/4

= 8 ¼ hours = 8 hour 15 minutes

Time and work Quantitative aptitude question

[Q] A can do a piece of work in 20 days. B is 25% more efficient than A. The number of days taken by B to do the same piece of work is?

(a) 14 days
(b) 15 days
(c) 16 days
(d) 13 days

Solution

Answer   (c)
Explanation
----
Work done by A in 1 day = 1/20

Work done by B in 1 day = (1/20) × (125/100) = 5/80 = 1/16

=> B can complete the work in 16 days

Time and work Quantitative aptitude question

[Q] If A, B and C can complete a piece of work in 24, 6 and 12 days respectively. Then, working together, they will complete the same work in how many days?
(a) 3 ³⁄₇
(b) 2 ³⁄₇
(c) 5 ³⁄₇
(d) 4 ³⁄₇

Solution

Answer   (a)
Explanation
----
Work done by A in 1 day = 1/24

Work done by B in 1 day = 1/6

Work done by C in 1 day = 1/12

Work done by A,B and C in 1 day = 1/24 + 1/6 + 1/12 = 7/24

=> Working together, they will complete the work in 24/7 days = 3 ³⁄₇ days

Time and work Quantitative aptitude question

[Q] If A is 30% more efficient than B. How much time will they, working together, take to complete a job which A alone could have done in 23 days?
(a) 23 days
(b) 13 days
(c) 33 days
(d) 43 days

Solution

Answer   (b)
Explanation
----
Work done by A in 1 day = 1/23

Let work done by B in 1 day = b

b × (130/100) = 1/23

=> b = 100/(23×130) = 10/(23×13)

Work done by A and B in 1 day = 1/23 + 10/(23×13) = 23/(23×13)= 1/13

=> A and B together can do the work in 13 days

Time and work Quantitative aptitude question

[Q] A can finish a work in 18 days and B can do the same work in 15 days. B worked for 10 days and left the job. In how many days, A alone can finish the remaining work?
(a) 4
(b) 2
(c) 5
(d) 6

Solution

Answer   (d)
Explanation
----
Work done by A in 1 day = 1/18

Work done by B in 1 day = 1/15

Work done by B in 10 days = 10/15 = 2/3

Remaining work = 1 – 2/3 = 1/3

Number of days in which A can finish the remaining work = (1/3) / (1/18) = 6