Q) Dev completed the school project in 20 days. How many days will Arun take to complete the same work if he is 25% more efficient than Dev?

a) 10 days              b) 12 days               c) 16 days                     d) 15 days

Ans:

Method 1:

Since Arun is 25% more efficient, hence work done by Arun is 1.25 times of Dev

or time taken by Arun is 1/1.25 of time taken by Dev

Since Dev takes 20 days to do a work,

∴ Arun will do the piece of work = 20/1.25 = 16 days

Hence, Answer is [B]

Method 2:

Ratio of time taken by Dev & Arun: 20: A :: 125:100

(since, Arun is 25% more efficient, she will take 25% less time than Dev)

∴ 20 : A = 5 : 4

∴ A = 20 x 4 /5 = 16 days

Hence, Answer is [B].

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