Math

posted by .

Bill can mow his mothers lawn in 6 minutes. His brother Jim can mow it in 9 minutes. How long will it take them to do it together, if each has his own lawnmower? (record answer in minutes rounded to one decimal place. For example 14.2835 minutes, record 14.3).

  • Math -

    Bill's rate = lawn/6
    Jim's reate = lawn/9
    combined rate = lawn/6 + lawn/9
    =5lawn/18

    Time for combined effort = lawn/[5lawn/18]
    = 18/5 minutes
    = 3.6 minutes

    Notice that "lawn" canceled, so we could have used any constant for "lawn"

    in general for individual times of a,b,c,.. units of time

    the time for a combined effort would be
    1/[1/a + 1/b + 1/c + ...] units of time

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math Project..Please help me..

    1. Samuel is 2/3 as old as his brother. In five years, he will be 3/4 as old as his brother will be. Find their present ages. a. If x = the brother’s age now, write an expression for Samuel’s present age in terms of x. b. Write …
  2. Math

    someone can mow his lawn in 48 minutes. if his daughter helps, they can do it in 40 minutes, how long would it take for his daughter to mow the lawn by herself?
  3. Algebra 1

    You can mow your whole lawn in 45 minutes, and your neighbor can mow your whole lawn in 30 minutes. How long would it take you to mow the lawn together?
  4. college intermediate algebra

    Working together, two people can mow the lawn in 24 minutes. Working alone, one person takes 20 minutes longer than the other. How many minutes would it take each person to mow the lawn alone?
  5. MATH

    Abe can mow the lawn in 15 minutes. Ben can mow the lawn in 20 minutes.Carl can mow the lawn in 30 minutes.They work together for 5 minutes.What part of the lawn was mowed?
  6. math

    Abe can mow the lawn in 15 minutes.Ben can mow the lawn in 20 minutes.Carl can mow the lawn in 30 minutes.They work together for 5 minutes.What part of the lawn was mowed?
  7. Algebra

    Bill can mow his mother's lawn in 45 minutes. His brother Jim can mow it in 75 minutes. How long will it take them to do it together?
  8. math

    Bill can mow his mother's lawn in 45 minutes. His brother Jim can mow it in 65 minutes. How long will it take them to do it together, if each has his own lawnmower?
  9. Algebra

    Betty can mow a lawn in 90 minutes. Melissa can mow the same lawn in 60 minutes. How long does it take for both Betty and Melissa to mow the lawn if they are working together?
  10. Algebra

    Richard takes 35 minutes to mow a lawn, but with the help of his friend Joe it only took him 15 minutes. If Joe worked alone, how long would it take Joe to mow the same lawn?

More Similar Questions