Walking at 3/5 of his usual speed, a person reaches his office 20 minute late than the usual time. His usual time in minute is:
Show answer & explanation
Correct answer: C
Explanation
Correct Answer is option 3 i.e.30
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Concept |
Understanding |
Application |
Fair calculation |
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Time = Distance/Speed |
Let the usual speed of the person be S Distance = D
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Speed of the person after decreasing = 3S/5 D/(3S/5) – D/S = 20 5D/3S – D/S = 20 ⇒2D/3S = 20 ∴D/S = 20 × 3/2 = 30 min |
20 × 3/2 = 30 |