SravnaTestPrep wrote:

A and B together can complete one-ninth of a job in a day. What is the difference between the maximum and minimum number of days A could take to complete the job alone, if A and B take whole number of days to complete the job alone?

A 45

B.60

C.80

D.90

E.Cannot be determined

Given, A & B together can complete 1/9th of the job in one day.

Let the job consist of 90 units. Therefore in one day A & B together can produce 10 units.

A & B together work at a rate of 10 units/day

So the combinations for the no. of units per day produced by A & B can be (1,9), (2,8), (3,7), (4,6), (5,5), (6,4), (7,3), (8,2), (9,1)

So Maximum units produced per day by A = 9 units/ day at its highest efficiency.

Hence to complete 90 units, A will take (90/9) = 10 days, this is the fastest for A at its highest efficiency.

So Minimum Days to finish the job = 10 days

Now, Similarly, minimum units produced per day by A = 1 unit/ day at its lowest efficiency.

Hence to complete 90 units, A will take (90/1) = 90 days, this is the slowest for a its lowest efficiency.

So Maximum Days to finish the job = 90 days

Required is Difference of Max Days & Min Days = 90 - 10 = 80

Answer C

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