SATHEE: Quantitative Aptitude Ques 1727

Quantitative Aptitude Ques 1727

Question: A train covers a distance in 1 h 40 min, if it runs at a speed of 96 km/h on an average. Find the speed at which the train must run to reduce the time of journey to 1 h 20 min.

Options:

A) 120 km/ h

B) 90 km/h

C) 144 km/h

D) 150 km/h

E) None of these

Show Answer

Answer:

Correct Answer: E

Solution:

Here, the person covers $ \frac{1}{2} $ of his journey at $ 40km/h, $ $ \frac{1}{3} $ at $ 60km/h $ and rest $ ( 1-\frac{1}{2}-\frac{1}{3}=\frac{1}{6} ) $ at $ 30km/h. $

$ \therefore $ Average speed for whole journey $ =\frac{1}{\frac{1}{2\times 40}+\frac{1}{3\times 60}+\frac{1}{6\times 30}}=\frac{1}{\frac{1}{80}+\frac{1}{180}+\frac{1}{180}} $ $ =\frac{720}{9+4+4}=\frac{720}{17}=42.35km/h $

Quantitative Aptitude Ques 1726

Quantitative Aptitude Ques 1728

Quantitative Aptitude Ques 1727

Question: A train covers a distance in 1 h 40 min, if it runs at a speed of 96 km/h on an average. Find the speed at which the train must run to reduce the time of journey to 1 h 20 min.

Options:

Answer:

Solution:

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