A car travels 100 km at a speed of 60 km/h and returns with a speed of 40 km/h. Calculate the average speed for the whole journey.

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Solution

Time taken to go =hr =hr
Time taken to return = hr
Total distance = (100 + 100) km = 200 km
total time taken = ( $\frac{5}{3}$ + $\frac{5}{2}$ )hr = hr
average speed = $fraction numerator t o t a l space d i s tan c e over denominator t o t a l space t i m e end fraction$
= $fraction numerator 200 over denominator begin display style 25 over 6 end style end fraction fraction numerator 200 cross times 6 over denominator 25 end fraction$

= 48 km/hr
Hence, the average speed is 48 km/hr.

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A car travels 100 km at a speed of 60 km/h and returns with a speed of 40 km/h. Calculate the average speed for the whole journey.

Time taken to go =hr =hr Time taken to return = hr Total distance = (100 + 100) km = 200 km total time taken = (53 + 52)hr = hr average speed = = = 48 km/hr Hence, the average speed is 48 km/hr.