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A boy travels between point A and point B at a speed of 6 km/h and returns at a speed of 9 km/h. If the total time taken by him is 1 hour 15 min, the distance between A and B is:

Solution

✅ Correct Option: 3

The boy travels from A to B at 6 km/h and returns at 9 km/h. The total time taken is 1 hour 15 minutes.

Convert 1 hour 15 minutes to hours:

1+1560=1.251 + \frac{15}{60} = 1.25 hours


Let the distance between A and B be dd km.

Time taken to go from A to B:

d6\frac{d}{6} hours

Time taken to return from B to A:

d9\frac{d}{9} hours

Total time:

d6+d9=1.25\frac{d}{6} + \frac{d}{9} = 1.25


The LCM of 6 and 9 is 18.

d6=3d18\frac{d}{6} = \frac{3d}{18}

d9=2d18\frac{d}{9} = \frac{2d}{18}

3d18+2d18=1.25\frac{3d}{18} + \frac{2d}{18} = 1.25

5d18=1.25\frac{5d}{18} = 1.25


5d18=1.25\frac{5d}{18} = 1.25

5d=1.25×185d = 1.25 \times 18

5d=22.55d = 22.5

d=22.55d = \frac{22.5}{5}

d=4.5d = 4.5

Therefore, the distance between A and B is 4.5 km.

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