SOLUTION: Please help me solve this word problem? Alan and Dave leave from the same point driving in opposite directions, Alan driving at 55 miles per hour and Dave at 65 mph. Alan has a one
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Question 789186: Please help me solve this word problem? Alan and Dave leave from the same point driving in opposite directions, Alan driving at 55 miles per hour and Dave at 65 mph. Alan has a one-hour head start. How long will they be able to talk on their car phones if the phones have a 250-mile range.
Test on Tuesday. Thanks for all your help.
Michael Armani Found 2 solutions by rothauserc, josmiceli:Answer by rothauserc(4718) (Show Source):
You can put this solution on YOUR website! we use rate * time = distance
Alan has a head start of one hour which equals 55 miles
250 - 55 = 195 miles
55t + 65t = 195
120t = 195
t = 1.625
so they will be able to talk for 1.625 +1 = 2.625 hours
You can put this solution on YOUR website! You need an equation for Alan and an equation for Dave
You want to know when they are mi apart
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First, you want to know how much of a head start Alan has
Let = his head start mi
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Start a stopwatch when Dave leaves
Let = time on stopwatch when they are mi apart
Let = distance that Dave has traveled
when they are mi apart = Alan's distance from starting point when
they are mi apart
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Alan's equation:
(1)
( note that I had to subtract his head start )
Dave's equation:
(2)
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Substitute (2) into (1)
(1)
(1)
(1) hrs
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They can talk for 1 hr 37 min 30 sec
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check:
(2)
(2)
(2)
and
(1)
(1)
(1)
(1)
(1)
OK
