Multiple choice

M takes 60% more time than N to complete a wall. If together they complete the wall in 24 days, then how many days will N alone take to complete it?

  1. 36 days

  2. 39 days

  3. 42 days

  4. 34 days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let N take x days. M takes 1.6x days. Their rates are 1/x and 1/(1.6x). Together: 1/x + 1/(1.6x) = 1/24. (1.6 + 1) / 1.6x = 1/24. 2.6 / 1.6x = 1/24. 2.6 * 24 / 1.6 = x. x = 39.

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