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SSC Selection Post 2024 PYQ — Question 65

SSC Selection Post - Higher Secondary Level - 24 June 2024 - Shift 2 • Quantitative Aptitude • Q65

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The speed of a boat in still water is 6 km/h, and the speed of the stream is 1.5 km/h. In going from point A to point B and returning to A, the boatman takes 2 hours and 40 minutes. Find the distance between points A and B.

Show answer & explanation

Correct answer: A

Explanation

The correct answer is Option 1 i.e. 7.5 km.

Let distance = D km

Downstream speed = 6 + 1.5 = 7.5 km/hr

Upstream speed = 6 - 1.5 = 4.5 km/hr

Time taken = D7.5+D4.5{D\over 7.5}+{D\over4.5} = 838\over3

⇒ 6D+10D45{6D+10D\over 45} = 838\over3

⇒ 16D45{16D\over 45} = 838\over3

⇒ D = 7.5 km