Multiple choice

X and Y together can complete a work in 12 days. X alone can complete in 20 days. If Y does the work only half a day daily, then in how many days X and Y together will complete the work? X और Y एक साथ 12 दिनों में एक काम पूरा कर सकते हैं। अकेले X, 20 दिनों में इसे पूरा कर सकता है यदि Y केवल प्रतिदिन आधे दिन काम करता है, तो कितने दिनों में X और Y एक साथ काम पूरा करेंगे?

  1. 10 days/दिन

  2. 20 days/दिन

  3. 11 days/दिन

  4. 15 days/दिन
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Combined rate: X + Y = 1/12 work/day. X's rate = 1/20 work/day. So Y's rate = 1/12 - 1/20 = 1/30 work/day. When Y works half-day: effective rate = 1/20 + (1/30 × 1/2) = 1/20 + 1/60 = 4/60 = 1/15. Time = 15 days. Option D is correct.

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