A bus travels between two cities in 6 hours at an average speed of 90

Question

A bus travels between two cities in 6 hours at an average speed of 90 kilometers per hour. If the bus returns by the same route at an average speed of 100 kilometers per hour, how long does the return trip take?

A. 5 hr 54 min
B. 5 hr 50 min
C. 5 hr 40 min
D. 5 hr 24 min
E. 5 hr

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Bunuel · Answer

The distance between the cities is 6 * 90 = 540 kilometers. Hence, the return trip would take 540/100 = 5.4 hours, which is 5 hours and 0.4 of an hour (0.4 of 60 minutes). Thus, the total time is 5 hours and 24 minutes.

Answer: D.

jaideeppal7 · Answer

Here Distance is fixed.

So

S1 * T1 = S2 * T2
90*6=100*T2
T2=5.4
=5hr+0.4*60min=5+24=5hr24min

SotJake · Answer

Rate (mph) 
 Time (hr) 
 Distance (miles) 
 
   First Trip 
 
  90  
  6  
   90	imes 6 = 540   
 
   Return Trip 
 
  100  
   \frac{540}{100} = 5.4   
  540

Hence, the time would be  5  hours and  40\%  of an hour.
Now, since   100\%   of an hour is   60  minutes ,   10\%   must be   \frac{60}{10} = 6  minutes . Hence,   40\%   is   4 	imes 6 = 24  minutes .
Thus,  (D) 5 hr 24 min .

SotJake · Answer

Also, a quick way to think about this is that since the distance is the same, rate and time would be inversely proportional to each other. Since going from 100 to 90 is a 10% decrease, the same would occur to the 6 hours. That said, 10% of 6 hours is \(6 \times 6\) minutes \(= 36\) minutes. Thus,

\(6 \text{ hours} - 36 \text{ minutes} = 5 \text{ hours } 24 \text{ minutes}\)

6 	ext{ hours} - 36 	ext{ minutes} = 5 	ext{ hours } 24 	ext{ minutes}

	Rate (mph)	Time (hr)	Distance (miles)
First Trip	\(90\)	\(6\)	\(90\times 6 = 540\)
Return Trip	\(100\)	\(\frac{540}{100} = 5.4\)	\(540\)

A bus travels between two cities in 6 hours at an average speed of 90

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A bus travels between two cities in 6 hours at an average speed of 90

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