SOLUTION: two families who lived 63 miles apart met at a park between their homes for a picnic. how long did each drive if both travelled at a rate of 45 miles an hour and one drove 12 minut

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: two families who lived 63 miles apart met at a park between their homes for a picnic. how long did each drive if both travelled at a rate of 45 miles an hour and one drove 12 minut      Log On


   



Question 1065649: two families who lived 63 miles apart met at a park between their homes for a picnic. how long did each drive if both travelled at a rate of 45 miles an hour and one drove 12 minutes longer than the other? how to solve it?

Found 2 solutions by rothauserc, josmiceli:
Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
use rate * time = distance
:
r(1) * t(1) + r(2) * t(2) = 63
:
12 minutes = 12 / 60 = 1 / 5 = 0.2 hour
:
we are given r(1) = r(2) = 45, t(1) = t + 0.2 and t(2) = t
:
45(t + 0.2) + 45t = 63
:
45t + 9 + 45t = 63
:
90t = 54
:
t = 54 / 90 = 6 / 10 = 0.6
:
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family one drove 0.8 hour or 48 minutes
:
family two drove 0.6 hour or 36 minutes
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:

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = the distance in miles that the
one who drove for the shorter time traveled
+63+-+d+ = the distance in miles the one
who drove for the longer time traveled
Let +t+ = time in hrs that the one who
drove for the shorter time traveled
+t+%2B+12%2F60+ = time in hrs that the one
who drove for the longer time traveled
----------------------------------------
(1) +d+=+45t+
(2) +63+-+d+=+45%2A%28+t+%2B+1%2F5+%29+
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( note that +12%2F60+=+1%2F5+ )
(2) +63+-+d+=+45t+%2B+9+
(2) +d+%2B+45t+=+54+
Substitute (1) into (2)
(2) +45t+%2B+45t+=+54+
(2) +90t+=+54+
(2) +t+=+3%2F5+ hrs
Convert to minutes
(2) +t+=+%28+3%2F5+%29%2A60+
(2) +t+=+36+ min
and
+36+%2B+12+=+48+
----------------------
One drove for 36 min
The other drove for 48 min
---------------------------
check:
(1) +d+=+45t+ ( +t+ must be in hrs here )
(1) +d+=+45%2A%283%2F5%29+
(1) +d+=+27+ mi
and
(2) +63+-+d+=+45%2A%28+t+%2B+1%2F5+%29+
(2) +63+-+d+=+45%2A%28+3%2F5+%2B+1%2F5+%29+
(2) +63+-+d+=+%28+4%2F5+%29%2A45+
(2) +63+-+d+=+36+
(2) +d+=+63+-+36+
(2) +d+=+27+ mi
OK