Must Know Time and Work Question Types | IBPS PO 2018

Time and Work Problems are one of the fundamental topics that banking aspirants can expect to be present in any examination, including the IBPS PO 2018 examination. Candidates are likely to overlook this topic because time and work problems appear to be simple. However, the examination setters can choose to make it difficult if they want. Hence, this blog post focuses on the two types of time and work problems that are a must know if an aspirant wants to crack their banking examinations.

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Time and Work Question Type 1

The first kind of question in the time and work problems topic is about the computation of time in the number of days as opposed to the number of hours per day. Consider this example below to better understand the concept.

A can complete a work by working 8 hours per day for 5 days while B can do the same task by working 6 hours per day for 4 days. How many days do they need to finish the task if they work together for about 7.5 hours per day?

A can complete the work in = 10*8 = 80 hours

B can complete the work in = 12*4 = 48 hours

But,

A’s 1 hour of work = 1/80

B’s 1 hour of work = 1/48

So, A and B combined work in 1 hour = 1/40 + 1/24 = 8/240

So, if about 8/240 of the work can be done in 1 hour, how much time would it take for the entire work to be done? This can be computed through cross – multiplication.

1/x = (8/240)/1

So, x = 240/8 = 30 hours

Now, we need to find out how long in days would they take if they were to be working 7.5 hours a day. This too may be computed by this logic –

7.5/30 = 1/x

7.5*x = 30

So, x = 30/7.5 = 4 days

Hence, when working for 7.5 hours, they would be able to finish the task in 4 days.

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Time and Work Question Type 2

The second kind of question in time and work problems are about equation-based questions pertaining to time and work. To understand, consider this question below and note how it can be solved. The method of solving the question is not much different from that of other question types, but there is a slight change.

A and B can finish a task together in 10 days, B and C can finish the same in 14 days, and A and C can finish it in 16 days. How many days shall A, B, and C require to finish it separately?

Let work done by A in 1 day be ‘x’, work done by B in 1 day be ‘y’, and work done by C in 1 day be ‘z’.

So, A and B need 10 days to complete a task.

And, work done by A and B in 1 day is = x + y = 1/10 (equation 1)

Similarly, B and C need 14 days to complete the same task.

So, work done by B and C in 1 day is = y + z = 1/14 (equation 2)

Lastly, C and A need 16 days to complete the same task.

So, work done by C and A in 1 day is = z + x = 1/16 (equation 3)

Adding equation 1, equation 2, and equation 3, we get –

x + y + y + z + z + x = 1/10 + 1/14 + 1/16

2*(x + y + z) = 131/560

So, (x + y + z) = 131/1120 (equation 4)

Now, compute (equation 4) – (equation 1), and we have –

(x + y + z) – (x + y) = z = 131/1120 – 1/10 = 19/1120

Substitute value of z = 19/1120 in (equation 2), we have –

(y + z) = 1/14

(y + 19/1120) = 1/14

So, y = 1/14 – 19/1120

And y = (80 – 19)/1120 = 61/1120

Lastly, substitute value of z in (equation 3) to compute for x –

(x + z) = 1/16

(x + 19/1120) = 1/16

So, x = 1/16 – 19/1120 = (70 – 19)/1120 = 51/1120

So, A can finish a work in 1120/51 days, B can finish the same work in 1120/61 days, and C can finish the same work in 1120/131 days.

Therefore, those are the 2 kinds of questions that you must know in the examination to ace the topics of time and work. 

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