Results 1 to 2 of 2

Thread: The average of A and B is 10...

  1. #1
    Member
    Joined
    Sep 2006
    Posts
    75

    The average of A and B is 10...

    The average (arithmetic mean) of A and B is 10, whereas the average of B and 10 is C/2. What is the average of A and C?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Global Moderator

    Joined
    Nov 2005
    From
    New York City
    Posts
    10,616
    Thanks
    10
    Quote Originally Posted by ceasar_19134 View Post
    The average (arithmetic mean) of A and B is 10, whereas the average of B and 10 is C/2. What is the average of A and C?
    This looks like a SAT question.

    $\displaystyle \frac{A+B}{2}=10$
    $\displaystyle \frac{B+10}{2}=\frac{C}{2}$

    Thus,
    $\displaystyle A+B=20$ (1)
    $\displaystyle B+10=C$ (2)
    From (1) subtract (2),
    $\displaystyle A-10=20-C$
    $\displaystyle A+C=30$
    $\displaystyle \frac{A+C}{2}=15$
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 5
    Last Post: May 26th 2011, 05:11 AM
  2. Replies: 2
    Last Post: Mar 13th 2010, 04:49 AM
  3. Average Value
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 28th 2009, 04:06 AM
  4. Average Value
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 27th 2009, 10:14 AM
  5. average
    Posted in the Statistics Forum
    Replies: 3
    Last Post: Mar 20th 2009, 04:20 AM

Search Tags


/mathhelpforum @mathhelpforum