SOLUTION: A motorist travels a distance of 120 miles. Had she increased her average speed by 10 mi/hr she would have cut 36 minutes off of her travel time. Find her average speed.
Algebra.Com
Question 319987: A motorist travels a distance of 120 miles. Had she increased her average speed by 10 mi/hr she would have cut 36 minutes off of her travel time. Find her average speed.
Found 2 solutions by mananth, MathTherapy:
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
let her speed be x
increased speed = x+10
distance traveled=120 miles
36/60 = 3/5 hours
..
time taken with increased speed= original time -3/5 hours
120/x+10= 120/x -3/5
120/x+10=600-3x /5x
5x*120=(x+10)(600-3x)
600x=600x-30x+6000-3x^2
3x^2+30x-6000=0
x^2+10x-2000=0
x^2+50x-40x-2000=0
x(x+50)-40(x+50)=0
(x+50)(x-40)=0
x=40 mph
Answer by MathTherapy(10551) (Show Source): You can put this solution on YOUR website!
A motorist travels a distance of 120 miles. Had she increased her average speed by 10 mi/hr she would have cut 36 minutes off of her travel time. Find her average speed.
Let her average speed be S
Then we'll have: ----->
Multiply by LCD, 5S(S + 10) to get: 120(5)(S + 10) - 3S(S + 10) = 120(5S)
----- Dividing by GCF, 3
----- (S + 50)(S - 40) = 0
Ignoring the negative value (- 50), we get S, or average speed as: mph
------------------
Check
------------------
Initial speed: 40 mph
Time taken: 120/40 = 3 hours
Increased speed = 50 (40 + 10)mph
New time = 120/50 = 2.4 hours
Difference in travel times = .6 hour (3 - 2.4)
.6 hour = = 36 minutes
RELATED QUESTIONS
By increasing his average speed by 10 mi/hr, a motorist could save 36 minutes in... (answered by jorel1380)
system of linear equations
A cyclist traveled a certain distance at her usual speed.... (answered by josgarithmetic,MathTherapy)
A teacher drove 280 miles to attend a conference and arrived 1 hour late. The teacher... (answered by josmiceli,MathTherapy)
By increasing the average speed of motorista by 10 miles per hour he would have save 36... (answered by stanbon,MathTherapy)
A motorist travels 120 miles from Antwerp to Brussels at an average speed of 48 mph. She... (answered by ReadingBoosters)
Betty ann drove from city A TO B a distance of 250 miles she increased her speed by 10... (answered by greenestamps,swincher4391,Theo,MathTherapy)
the speed 90 mi/hr. in 10 minutes it travels a distance... (answered by MathLover1,Alan3354)
A women drives her snowmoble 150 miles at the rate of r mph. She could have gone the same (answered by stanbon)
Hello. I have a math question for you
Kathryn leaves her home and travels at an... (answered by stanbon,solver91311)