CAT Exam Model Paper 6 with solutions for free online practice

Question : 8 of 60

Marks: +1, -0

John and David work on alternate days with John starting on the first day. John does 12.5% of the total work on the last day and finishes the work. If John alone can do the work in 6 days then which of following can be the number of days in which David alone can do the whole work?

24 days
12 days
8 days
10 days

Validate

Solution:

Let us assume that the total work is 24x units. So John will do 12.5% of 24x = 3x work on the last day.
Since John alone can do the work in 6 days, so he will do 4x units of work per day.

21 x units of work is done in 2 or 4 or 6 or 8 or 10 days. Beyond this John alone would have done more than 21 x units of work.
2 days ⇒ David 17x in 1 day ⇒ Working alone it would take him

24/17

days
4 days ⇒ David 6.5x in 1 day ⇒ Working alone it would take him

48/13

days
6 days ⇒ David 3x in 1day ⇒ Working alone itwould take him 8 days
8 days ⇒ David 1.25x In 1day ⇒ Working alone it would take him

96/5

days
10 days ⇒ David

x/5

in 1 day ⇒ working alone it would take him 120 days

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