Results 1 to 4 of 4

Math Help - Pre-Algebra Placement Test problem

  1. #1
    Newbie
    Joined
    Nov 2010
    Posts
    18

    Pre-Algebra Placement Test problem

    I'm preparing for college and I got stuck on one of the problems of Pre-Algebra Placement Test.. So can someone please help me find the solution to it.

    A total of 50 juniors and seniors were given a mathematics test. The 35 juniors attained an average score of 80 while the 15 seniors attained an average of 70. What was the average score for all 50 students who took the test?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Master Of Puppets
    pickslides's Avatar
    Joined
    Sep 2008
    From
    Melbourne
    Posts
    5,234
    Thanks
    27
    You have n_j = 35, n_s = 15, \bar{x}_j = 80 , \bar{x}_s = 70

    Working backwards with the formula for the mean i.e.  \bar{x} = \frac{\sum x}{n}

     \displaystyle\bar{x}_j = \frac{\sum x_j}{n_j}\implies 80 = \frac{\sum x_j}{35}\implies \sum x_j = 80\times 35

     \displaystyle\bar{x}_s = \frac{\sum x_s}{n_s}\implies 70 = \frac{\sum x_s}{15}\implies \sum x_s = 70\times 15

    Now for the mean of both (the total)

    \displaystyle\bar{x} = \frac{\sum x_j+\sum x_s}{n_j+n_s} = \frac{80\times 35+70\times 15}{35+15}= \dots
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by Aravsion View Post
    I'm preparing for college and I got stuck on one of the problems of Pre-Algebra Placement Test..
    What is the purpose of a Pre-Algebra Placement Test?

    CB
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Nov 2010
    Posts
    18
    Quote Originally Posted by CaptainBlack View Post
    What is the purpose of a Pre-Algebra Placement Test?
    The purpose is to prepare for college. The problems I've done in like 8 or 9 grade I forgot how to do and its all thanks to the education we get here in U.S. schools.
    So, that is why so many people in school have problems with mathematics and second grade problems.
    Last edited by Aravsion; November 7th 2010 at 03:49 PM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. College Placement Test (COMPASS)
    Posted in the Algebra Forum
    Replies: 2
    Last Post: May 5th 2010, 07:43 PM
  2. Placement And Displacement
    Posted in the Calculus Forum
    Replies: 3
    Last Post: January 8th 2010, 08:48 PM
  3. Compass Placement Test
    Posted in the Algebra Forum
    Replies: 1
    Last Post: January 5th 2009, 04:22 PM
  4. seating placement
    Posted in the Statistics Forum
    Replies: 2
    Last Post: October 5th 2008, 08:11 PM
  5. Placement tests
    Posted in the Pre-Calculus Forum
    Replies: 5
    Last Post: June 18th 2007, 12:04 PM

Search Tags


/mathhelpforum @mathhelpforum