SOLUTION: Going to the airport, a car hits a hole damaging the front right wheel. The temporary tire decreases the average speed by 15 mph. If the 39 mile drive to the airport usually takes

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Going to the airport, a car hits a hole damaging the front right wheel. The temporary tire decreases the average speed by 15 mph. If the 39 mile drive to the airport usually takes       Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 1024693: Going to the airport, a car hits a hole damaging the front right wheel. The temporary tire decreases the average speed by 15 mph. If the 39 mile drive to the airport usually takes 45 minutes, how much time should be budgeted for the drive home from the airport.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = the normal speed to get to airport on time
Let +t+ = time in hrs to get to airport with decreased speed
(1) +39+=+s%2A%283%2F4%29+
(2) +39+=+%28+s+-+1%2F4+%29%2At+
----------------------
(2) +39+=+s%2At+-+%281%2F4%29%2At+
(2) +156+=+4s%2At+-+t+
and
(1) +39+=+s%2A%283%2F4%29+
(1) +156+=+3s+
(1) +s+=+52+
---------------
Plug this result into (2)
(2) +156+=+4s%2At+-+t+
(2) +156+=+4%2A52%2At+-+t+
(2) +156+=+208t+-+t+
(2) +156+=+207t+
(2) +t+=+.7536+
+.7536%2A60+=+45.217+
+.217%2A60+=+13+
The time home from airport will be
45 min and 13 sec
----------------
check:
(2) +39+=+%28+s+-+1%2F4+%29%2At+
(2) +39+=+%2852+-+.25+%29%2A.7536+
(2) +39+=+51.75%2A.7536+
(2) +39+=+38.998+
Error due to rounding off