Two persons A and B working separately can sanitise a building in 6 and 10 hours, respectively. They work in stretches of one hour alternately. If A begins at 8 a.m., when will the work be finished?

Question

Question

This question was previously asked in

SSC CGL 2022 Tier-I Official Paper (Held On : 13 Dec 2022 Shift 3)

Answer 1

Given:

Person A can sanitize a building = 6 h

Person B can sanitize a building = 10 h

Concept used:

Efficiency × Time = Total work

Calculation:

Now, according to the question:

⇒ (5 + 3) = 8 units = 2 hours

⇒ 2 hours = 8 units

so

⇒ 6 hours = 8 × 3 = 24 units

till 7th hours, work completed = 24 + 5 = 29 units

Remaining work = 30 - 29 = 1 unit

1 unit of work is completed by B in 1/3 hour.

Total time is taken to complete the total work = 7\(1\over3\) hours

∴ The correct answer is 7\(1\over3\) h.

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