SOLUTION: Jamie recently drove to visit her parents who live 390 miles away. On her way there her average speed was 11 miles per hour faster than on her way home (she ran into some bad weath

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Jamie recently drove to visit her parents who live 390 miles away. On her way there her average speed was 11 miles per hour faster than on her way home (she ran into some bad weath      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 802147: Jamie recently drove to visit her parents who live 390 miles away. On her way there her average speed was 11 miles per hour faster than on her way home (she ran into some bad weather). If Jamie spent a total of 13 hours driving, find the two rates.
Found 2 solutions by mananth, MathTherapy:
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Jamie recently drove to visit her parents who live 390 miles away. On her way there her average speed was 11 miles per hour faster than on her way home (she ran into some bad weather). If Jamie spent a total of 13 hours driving, find the two rates.
distance = 390 miles
on her way there speed = x mph
time taken = 930/x
On her return speed was x-11 mph
time = 930/(x-11)

Time to go there + time to return = 13 hours
930/x +930/(x-11) = 13
Multiply by x(x-11)
930(x-11)+930x=13x(x-11)
930x-10230+930x=13x^2-143x
Re arrange
13x^2-1860x-143x+10230=0
13x^2-2003x+10230=0
Find the roots of the equation by quadratic formula

a= 13 b= -2003 c= 10230 2916

b^2-4ac= 4012009 - 531960
b^2-4ac= 3480049 sqrt%28%093480049%09%29= 1865.49
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29 )/
x1=( 2003 + 1865.49 )/ 26
x1= 148.79
x2=( 2003 - 1865.49 )/ 26
x2= 5.29
Ignore 5.29
x = 148.79 mph to go there
Return will be 11 mph less





Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
Jamie recently drove to visit her parents who live 390 miles away. On her way there her average speed was 11 miles per hour faster than on her way home (she ran into some bad weather). If Jamie spent a total of 13 hours driving, find the two rates.

Using S as the average speed on the return trip leads to the quadratic equation: S%5E2+-+49S+-+330+=+0, which when factored results in S, or average speed on return trip being: highlight_green%2855%29 mph, and average speed on trip to house being 55 + 11, or highlight_green%2866%29 mph

You can do the check!!

Send comments, “thank-yous,” and inquiries to “D” at MathMadEzy@aol.com. Further help is available, online or in-person, for a fee, obviously.

For FREE info and answers to questions about the ASVAB exam, the NYS 3 – 8 city/state wide exams, GENERAL MATH QUESTIONS, MATH HOMEWORK QUESTIONS, or MATH QUESTIONS related to the Regents Integrated Algebra, Regents Geometry, Regents Algebra 2/Trigonometry, SHSAT, COOP/HSPT/TACHS, PSAT, SAT, ACT, SSAT/ISEE, GRE, CLEP, and the GED, you can visit: http://asvabstudyzone.freeforums.net/.