Question 514713
Two planes leave LA at the same time. One heads to San Diego, the other to San Francisco. The San Francisco plane flies 50mph faster. In 1/2 hr, the planes are 275 miles apart. What are their speeds?
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To San Diego  DATA:
time = 1/2 hr ; rate =  r mph ; distance = t*r = (r/2) miles
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To San Fran DATA:
time = 1/2 hr ; rate = r+50 mph ; distance = t*r = (1/2)(r+50) miles
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Equation:
dist  + dist = 275 miles
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(r/2) + (r+50)/2 = 275
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Multiply thru by 2 to get:
r + r+50 = 550
2r = 500
r = 250 mph (speed of the plane to San Diego)
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r + 50 mph (speed of the plane to San Fran)
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Cheers,
Stan H.
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