A car averages 55 mph for the first 4 hours of a trip and
averages 70 mph for each additional hour. The average speed
for the entire trip was 60 mph. How many hours long is the trip?

Answer Posted / shyam

avg speed = (total distance)/(total time)

car first travels 4hrs.. let us assume it travels for nhrs
after 4 hrs.. So it keeps up an avg speed of 70mph for n hrs

hence 60 = (55+70n)/(4+n) => n = 18.5hrs

therefore total duration is 18.5 + 4 = 22.5hrs

Is This Answer Correct ?    4 Yes 23 No



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