2

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2

by likewhoa » Mon Nov 26, 2007 7:32 am
A car traveling at a certain constant speed takes 2 seconds longer to travel 1 kilometer than it would take to travel 1 kilometer at 75 km per hour. At what speed, in km/per hour, is the car traveling?


answer: 72

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Re: 2

by projase » Mon Nov 26, 2007 3:40 pm
likewhoa wrote:A car traveling at a certain constant speed takes 2 seconds longer to travel 1 kilometer than it would take to travel 1 kilometer at 75 km per hour. At what speed, in km/per hour, is the car traveling?


answer: 72
1 hour = 3600 seconds and v = d/T
T = d/V = 1km/75km/hr = 1/75 hour = 3600/75 seconds = 48 seconds
New time = 48 + 2 secons = 50seconds

New velocity = 1km/50secons = 1 km/(50/60 min) = 60/50 KM/min = 6/5 Km/ (1/60 hour) = 60*6/5 KM/Hr = 72
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