Multiple choice

K and L can do a work in 15 and 20 days, respectively. They work together for 5 days and leave. Calculate the unfinished portion of the work. k এবং L যথাক্রমে 15 এবং 20 দিনের মধ্যে একটি কাজ করতে পারেন। তারা একসাথে 5 দিন কাজ করে চলে যায়। কাজের অসম্পূর্ণ অংশ ?

  1. 7/12

  2. 5/12

  3. 1/13

  4. 1/4
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B Correct answer
Explanation

K's rate = 1/15, L's rate = 1/20. Combined rate = 1/15 + 1/20 = 7/60. Work done in 5 days = 5 * (7/60) = 35/60 = 7/12. Unfinished work = 1 - 7/12 = 5/12.

AI explanation

Let the total work be the least common multiple of 15 and 20, which is 60 units. K completes 4 units per day and L completes 3 units per day, so their combined daily work is 7 units. In 5 days working together, they complete 35 units, leaving 25 units of work unfinished. The unfinished portion is 25 divided by 60, which simplifies to 5/12.

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