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Mathematics
Speed, Time and Distance
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NTPC Graduate Tier 1 2025 Shift-1 📅 06 May, 2025

If Ishwar covers 721 km in a boat in 42 hours against the stream and he takes 15 hours with the stream, then find the speed of the stream.

A
7.38 km/hr
B
19.25 km/hr
C
22.48 km/hr
D
15.45 km/hr
Result Summary
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NTPC Graduate Tier 1
2025 • 06 May, 2025 • Shift-1
If Ishwar covers 721 km in a boat in 42 hours against the stream and he takes 15 hours with the stream, then find the speed of the stream.
Correct Answer
15.45 km/hr
Upstream Calculation: The upstream speed (against the current) is Distance divided by Time. So, 721 / 42 = 17.166... km/hr.Downstream Calculation: The downstrea......
Ref/Book : NTPC Graduate Tier 1 2025
Ref. Subject Mathematics
Chapter -
Ref. Topic Speed, Time and Distance
Pg. No -
💡 Analysis & Explanation
Upstream Calculation ▼
The upstream speed (against the current) is Distance divided by Time. So, 721 / 42 = 17.166... km/hr.
Downstream Calculation ▼
The downstream speed (with the current) is exactly 721 / 15 = 48.066... km/hr.
Stream Speed Formula ▼
The speed of the stream is derived by halving the difference between the downstream and upstream speeds: (Downstream Speed - Upstream Speed) / 2.
Final Derivation ▼
Applying the values: (48.066 - 17.166) / 2 = 30.9 / 2 = 15.45.
Conclusion ▼
The precise speed of the flowing stream is 15.45 km/hr.
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