Pairs of markings a set distance apart are made on highways so that police can detect drivers exceeding the speed limit. over a fixed? distance, the speed r varies inversely with the time t. in one particular pair of? markings, r is 66 mph when t is 66 seconds. find the speed of a car that travels the given distance in 55 seconds.

Question

Bailey Terry

Mathematics

25 January, 04:35

Pairs of markings a set distance apart are made on highways so that police can detect drivers exceeding the speed limit. over a fixed? distance, the speed r varies inversely with the time t. in one particular pair of? markings, r is 66 mph when t is 66 seconds. find the speed of a car that travels the given distance in 55 seconds.

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Answers (1)

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Hadassah Russell · Answer 1

R = k / t where r = speed, t = time and k is a constant

Given r = 66 when t = 66 so we have

66 = k / 66

so k = 66^2 = 4356

so when t = 55

speed r = 4356 / 55 = 79.2 mph