Results 1 to 5 of 5

Math Help - Advanced Percentage Problems

  1. #1
    Newbie
    Joined
    Jun 2009
    Posts
    2

    Advanced Percentage Problems

    1. a is what percent of b?

    2. What percent of a is 5?

    3. 20 is what percent more than 15?

    4. 2/5 is what percent of b?

    5. 15 is what percent less than 20?

    6. 1/2 is what percent more than 1/5?

    7. 2/3 is what percent less than 1 1/2?

    8. If a>b, what percent more than b is a?

    9. if a<b, what percent less than b is a?

    10. What is 40% more than 20%?

    11. What is 40% more than 20% of 40?

    12. What is 40% more than 40 less than 20% of 80?

    13. What is a% less than b% more than c?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Jan 2009
    Posts
    108
    Where is your work? Help me understand the trouble you are having by seeing what you are doing wrong.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member
    Joined
    May 2009
    Posts
    527
    For percent problems I find it helpful to use this mnemonic:

    \frac{percent}{100} = \frac{is}{of}

    What you do is you substitute numbers next to the words above into the proportion. So, for example:

    1. a is what percent of b?
    Substitute a for the "is", a variable for "percent", and b for "of".

    \frac{x}{100} = \frac{a}{b}

    x = \frac{100a}{b}

    So a is \frac{100a}{b} percent of b.


    2. What percent of a is 5?
    Substitute 5 for the "is", a variable for "percent", and a for "of".

    \frac{x}{100} = \frac{5}{a}

    x = \frac{500}{a}

    So \frac{500}{a} percent of a is 5.


    3. 20 is what percent more than 15?
    20 is 5 more than 15, so this is also asking "5 is what percent of 15?" Substitute 5 for the "is", a variable for "percent", and 15 for "of".

    \frac{x}{100} = \frac{5}{15}

    x = \frac{100}{3}

    x = 33.33...%

    So 20 is 33.33...% more than 15.

    That's all from me. You try the rest. Good luck!


    01
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Jun 2009
    Posts
    2
    I don't get anything. I mean, I don't how to do anything like these?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member great_math's Avatar
    Joined
    Oct 2008
    Posts
    132
    you can say: let a is x\% of b

    so a=\frac{x}{100}\cdot b

    so \frac{a}{b}=\frac{x}{100}

    or x=\frac{100a}{b}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Percentage Problems
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 17th 2010, 12:35 PM
  2. Need help with Percentage Word Problems.
    Posted in the Algebra Forum
    Replies: 5
    Last Post: October 13th 2009, 08:11 PM
  3. advanced geometry volume problems
    Posted in the Geometry Forum
    Replies: 1
    Last Post: April 29th 2008, 08:38 PM
  4. Replies: 1
    Last Post: March 11th 2008, 11:24 PM
  5. two word percentage problems?
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 10th 2008, 09:19 AM

Search Tags


/mathhelpforum @mathhelpforum