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Question
Pari needs 4 hours to complete the work. His friend Yuvan needs 6 hours to complete the same work. How long will it take to complete if they work together?
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Solution
Pari: time required to complete the work = 4 hrs.
∴ In 1 hr. she will complete = `1/4` of the work.
= `1/4"w"`.
Yuvan: Time required to complete the work = 6 hrs.
∴ In 1 hr. he will complete the = `1/6` of the work
= `1/6"w"`
Working together, in 1 hr. they will complete `"w"/4 + "w"/6` of the work.
= `(6"w" + 4"w")/24`
= `5/12` w
∴ To complete the total work time taken
= `"w"/(5/12"w")`
= `12/5`
= 2.4 hrs. ...[∵ (4) hrs = 4 × 60 = 24 min]
= 2 hrs 24 minutes.
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