A jogger ran 6 miles, decreased her speed by 1 mile per hour and than ran another 7 miles. If total jogging time was 2 1/42, find speed for each part of her run.

  1. 👍
  2. 👎
  3. 👁
  1. first speed --- x
    second speed --- x-1
    time at first speed = 6/x
    time at 2nd speed = 7/(x-1)

    6/x + 7/(x-1) = 2 1/42 = 85/42
    times: 42x(x-1)
    6(42)(x-1) + 7(42)x = 85x(x-1)
    252x - 252 + 294x = 85x^2 - 85x
    85x^2 - 631x + 252 = 0
    x = (631 ± √312481)/170
    = 7 or ...
    aha , it facored
    (x-7)(85x - 36) = 0
    x=7 or x = 36/85
    but 36/85 would make his 2nd speed negative, not very likeyly, so
    x = 7

    for the first leg he ran at 7 mph, for the 2nd leg he ran at 6 mph

    check: 6/7 + 7/6 = (36+49)/42 = 85/42 = 2 1/42

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. algebra

    A student runs 100 meters in 11 seconds. What is the speed of the student? speed = distance over time; 1 mile = 1609 meters 9.1 miles per hour 16 miles per hour 20.3 miles per hour 24 miles per hour pls help

  2. mathmatics

    Susie ran a race. She ran 555 miles an hour, and the race took her ttt hours to complete.How long was the race?

  3. History

    7.)Which answer best describes the U.S. National Road? A.)It ran from Atlanta to Baltimore and followed the railroad. B.)It ran from New York to Chicago and was made from wooden planks. C.)It ran from Massachusetts to Ohio and ran

  4. mathematics

    Write and solve an equation for the situation. Jamal and Keisha went running. Keisha ran 2.4 miles more than Jamal. If Keisha ran 8.5 miles, how many miles did Jamal run? A. 2.4 + 8.5 = m; m=10.9 miles B. 2.4 + m = 8.5; m = 6.1

  1. Math

    Can someone help me with these questions? Q: The sum of 7 and u is 14 Q: Jamal and Keisha went running. Jeusha ran 2.4 miles more than Jamal. If Keisha ran 8.5 miles, how many miles did Jamal run? Q: Phil solved the question x +

  2. math

    Leila ran three times last week. Here are the distances she ran (in kilometers). 16.1 ,5,8.92 What is the total distance Leila ran on these three days?

  3. algebra

    a cheetah ran 300 feet in 2.92 seconds. What was the cheetahs average speed in miles per hour? Please show steps.THANKS!!

  4. math

    Tina and Jim live 5 miles apart from each other. Tina ran from her house to Jim's house at a rate of 10 miles per hour. Jim ran from his house to Tina's house at a rate of 8 miles per hour. How far had Jim run by the time he

  1. Math

    Tia ran 2 and 7/8 miles. George ran 1 and 1/10 miles.About how many more miles did tia run than George? Place a star on the number line to show your estimate

  2. math!!!!

    One lap around the track is equal to 1/8 of a mile. A horse ran a distance of 9 laps in 2 minutes and 30 seconds. What was the horse's average speed in miles per minute?

  3. math

    A marathon runner ran 26.2 miles in 2 h 30 min. Find these rates: a. miles per hour b. miles per minute c. minutes per mile

  4. algebra

    Mike said, last week I ran 15 miles farther than Bill. Pete said Last week I ran one mile less than 3 times as far as Bill. If Mike and Pete ran the same distance, how far did Bill run?

You can view more similar questions or ask a new question.