Question 134600
Jan can run at 7.5m/s and Mary at 8.0m/s. On a race track Jan is given a 25m head start, and the race ends in a tie. How long is the track?
My chart
r * t =d
Jan:  7.5 t =7.5t+25
Mary 8.0 t =8.0t
7.5t+25=8.0t
-7.5t -7.5t
25=.5t
divide by .5 and I got 50 then I times that by 8.0 and got 400miles
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Jan can run at 7.5m/s and Mary at 8.0m/s. On a race track Jan is given a 25m head start, and the race ends in a tie. How long is the track?
Jan DATA:
rate = 60*7.5 meter/minute ; time = "t+ (25/60)" minutes ; distance = 450(t+(25/60)) = (450t + 187.5) meters
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Mary DATA:
rate = 60*8 meters/min ; time = t minutes : distance = 480t meters
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EQUATION:
distance = distance
450t+187.5 = 480t
30t = 187.5
t = 6.25 minutes
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How long is the track?
distance = 6.25 min * 480 meters/min = 3000 meters or 3 kilometers
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Cheers,
Stan H.