SOLUTION: I rode my bike 30 miles. If I had increased my average speed by 3 mph, I would have decreased my travel time by 20 minutes. How many miles per hour was my original speed?
I trie
Algebra ->
Customizable Word Problem Solvers
-> Travel
-> SOLUTION: I rode my bike 30 miles. If I had increased my average speed by 3 mph, I would have decreased my travel time by 20 minutes. How many miles per hour was my original speed?
I trie
Log On
Question 684235: I rode my bike 30 miles. If I had increased my average speed by 3 mph, I would have decreased my travel time by 20 minutes. How many miles per hour was my original speed?
I tried to use d= r* t so 3x=30? I don't know what else to do Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website! There are 2 equations. One is for the actual bike riding
the other is the option with higher speed.
Let = original speed in mi/hr
Let = original time in hrs
given:
(1)
(2)
( note that 20 min is 1/3 hr )
---------------------------
(2)
and
(1)
Substitute (1) into (2)
( note also that )
(2)
Subtract from both sides, then add to both sides
(2)
Multiply both sides by
(2)
(2)
Complete the square:
(2)
(2)
(2)
(2)
Take the square root of both sides ( ignore the negative square root )
(2)
(2)
(2)
Your original speed was 15 mi/hr
check:
(1)
(1)
(1)
and
(2)
(2)
(2)
(2)
(2)
(2)
OK
