A motorboat whose speed is 24km/hr in still water takes 1 hour more to go 32km upstream than to return downstream to the same spot find the speed of the stream
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Given That:
- Total Distance = 32km
- Speed in Still Water = 24km/h
ExPlanation:
Let the speed of the stream be ‘x’ km/h
then, Speed moving upstream = 24 - x
Speed moving downstream = 24 + x
Now for upstream journey
- Time taken = 32/24 - x hours
For downstream journey
- Time taken = 32/24 + x hours
Difference between timings = 1 hr.
Time of upstream journey = Time of downstream journey + 1 hr
Hence,
The equation becomes:
(32/24 - x) - (32/24 + x) = 1
➠ 1/32 = (1/24 - x) - (1/24 + x)
➠1/32 = (24 + x - 24 + x) / 242- x²
➠ 242 - x² = 64x
➠ x² + 64x - 576 = 0
On factorising we get:
x² + 72x - 8x - 576 = 0
➠ x(x + 72) - 8 (x + 72) = 0
➠ (x - 8)(x = 72) = 0
➠ x = 8 or x = -72
Speed cannot be negative
- Hence x = 8
Therefore,
- The speed of the stream is 8 km/hr
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