Geometry

posted by .

Use an indeirect proof to show that John exceeded the 55 MPH speed limit if he left his house at 8:15 a.m. and arrived at his office 60 miles away at 9:00 a.m.

Assume temporarily that John traveled at a constant speed of 55 mph and that was his maximum speed. Then in 45 minutes (8:15 am to 9:00 am), he would have traveled
55 * 3/4 = 41.25 miles and would not have made it to his office. But this contradicts the known fact that he must have traveled more than 55mph. Since he did make it to his office which is 60 miles away, he must have traveled more than 55 mph


Good job.

Thanks very much

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. algebra word problem: still stuck

    question: rachel allows herself 1 hour to reach a sales appt 50 miles away. after she has driven 30 miles, she realizes that she must increase her speed by 15mph in order to get there on time. what was her speed for the first 30 miles?
  2. Algebra 2

    two people, john and mary, are 200 miles apart and leave at the same time to meet. They are driving toward each other at constant rate on the same straight road. John is traveling at 45 mph and Mary is traveling at 35 mph. When they …
  3. Simple Math Question

    two people, john and mary, are 200 miles apart and leave at the same time to meet. They are driving toward each other at constant rate on the same straight road. John is traveling at 45 mph and Mary is traveling at 35 mph. When they …
  4. math

    There are two roads that connect Emily's house and John's house. Emily told john that she drove 3/4 of the total distance from her house to john's house on one day, but she did not tell him which road she took. A. using the long road, …
  5. Math to Ms.Sue

     Mark for review (Will be highlighted on the review page) 19.   Jim paddles from one shore of a lake three miles wide at 4 mph, and John paddles from the opposite shore at 5 mph. How long will they travel before they meet?
  6. Math help

    19.   Jim paddles from one shore of a lake three miles wide at 4 mph, and John paddles from the opposite shore at 5 mph. How long will they travel before they meet?
  7. Physics

    John takes off running towards his house that is 6 meters away. His initial velocity is 2m/s. How long will it take John to get to his hose (his orgin)?
  8. math

    John I'd running in a race. The race is 25miles long. After two hours, John has run 7 miles. How many miles, m, does John have left to run?
  9. Math Please Help!!!

    John is at a car show. Beginning 2.5 miles away, a car travelling at a constant 45 miles per hour approaches and then passes John. The distance between John and the car can be represented by the equation d = |2.5 – 45t|. At what …
  10. Algebra-Please Help!!!

    John is at a car show. Beginning 2.5 miles away, a car travelling at a constant 45 miles per hour approaches and then passes John. The distance between John and the car can be represented by the equation d = |2.5 – 45t|. At what …

More Similar Questions