Algebra-- PLEASE help!

posted by .

Pete's Plymouth travels 200 miles at a certain speed. If the car had gone 10 mph faster, the trip would have taken 1 hour less. Find Pete's speed.

I am very confused about how to solve this problem! Please explain well. Thank you so much!!! :-)

  • Algebra-- PLEASE help! -

    let his original speed be x mph
    then his original time is 200/x hours

    let his second speed be x+10 mph
    then his second time is 200/(x+10) hours

    so 200/x - 200/(x+10) = 1
    multiply both sides by x(x+10)

    200x + 2000 - 200x = x^2 + 10x
    x^2 + 10x - 2000 = 0
    (x-40)(x+50) = 0
    x = 40 or x= -50 (negative speed makes no sense)

    so Pete's speed is 40 mph.

    check: at 40 mph, it would take him 200/40 = 5 hours
    at 50 mph it would have taken him 200/50 = 4 hours.

    OK then!

  • Algebra-- PLEASE help! -

    Lat V be the slower speed and T be the time it takes to go 200 miles at that speed. You can write these two equations:

    T = 200/V

    T = 200/(V + 10) + 1

    Now get rid of the T and create and solve an equation for v alone.

    200 [1/V - 1/(V+10) = 1

    200(V + 10 - V) = V(V+10)
    V^2 + 10V -2000 = 0
    (V-40)(V+50) = 0
    V = 40 since only positive roots are allowed.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. algebra

    These are very easy to set up with a "chart" ---------Distance-----Rate---Time (D=RxT) slow way --6x----------x-------6 fast way - 5(x+7)-----x+7------5 so 6x = 5(x+7) 6x=5x+35+ x=35 The speed on the slower trip was 35 mph, and on …
  2. algebra

    Can someoe please help me figure this out?
  3. Math

    Pete and jan compete as a team in a biathlon. Pete runs at a speed of 9 km/ h for x hours. Jan cycles at twice Pete's running speed for 1 hour and 30 minutes. The total distance of the biathlon is 42 km. Find, in hour and minutes, …
  4. algebra d=rt word problem

    A car travels from one town to another at a speed of 32 mph. If it had gone 4 mph faster, it could have made the trip in 1/2 hour less time. How far apart are the towns.
  5. MATH Algebra

    The speed of a passenger train is 6 mph faster than the speed of a freight train. The passenger train travels 280 miles in the same time it takes the freight train to travel 250 miles. Find the speed of each train. What is the speed …
  6. algebra

    during the first trip a canoeist travels 79 miles at a certain speed. the canoist travels 24 miles on the second part of the trip at a speed of 5 mph slower. the total time for the trip is 5 hrs. what was the speed on each part of …
  7. Algebra

    During the first part of a trip, a canoeist travels 57 miles at a certain speed. The canoeist travels 13 miles on the second trip at a speed 5 mph slower. The total time for the trip is 5 hrs. what was the speed on each part of the …
  8. intermediate algebra

    The danville Express travels 280 miles at a certain speed.If te speed were increased by 5 mph the trip could have been made in 1 hr less time.What was the actual speed?
  9. math

    Suppose that a certain municipality uses the equation y=3(x-50)+30 to determine the fine assessed a car which exceeds the 50 mph speed limit. Let x=speed of the car (in mph) and y=corresponding fine in dollars. a)What is the fine for …
  10. Algebra

    A car travels from one town to another at a speed of 42 mph. If it had gone 6 mph faster, it could have made the trip in a half hour less time. How far apart are the towns?

More Similar Questions