Multiple choice

Aman, Simar and Karan can complete an assignment test in 18 days, 21 days and 15 days, respectively. They work together for 4 days. After that, Aman and Simar leave. In how many days will Karan alone complete the remaining test?

  1. 3.2 days

  2. 4 days

  3. 4.8 days

  4. 9.6 days

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Work rates: Aman=1/18, Simar=1/21, Karan=1/15. Combined rate = 1/18 + 1/21 + 1/15 = (35+30+42)/630 = 107/630. In 4 days, they do 4 * 107/630 = 428/630. Remaining work = 1 - 428/630 = 202/630. Karan's time = (202/630) / (1/15) = 202/630 * 15 = 202/42 = 4.809 days.

AI explanation

Let the total work be the least common multiple of 18, 21, and 15, which is 630 units. The daily work rates for Aman, Simar, and Karan are 35, 30, and 42 units respectively. Working together for 4 days, they complete 428 units, leaving 202 units of work. Karan alone must complete the remaining 202 units at his rate of 42 units per day, which takes 4.8 days.

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