Results 1 to 2 of 2

Math Help - Standard Deviation Problem

  1. #1
    Junior Member
    Joined
    Oct 2007
    Posts
    40
    Awards
    1

    Standard Deviation Problem

    I would appreciate your help on the following problem:

    A mason is contracted to build a patio retaining wall. Plans call for the base of the wall to be a row of 50 10-inch bricks, each separated by \frac{1}{2}-inch-thick mortar. Suppose that the bricks used are randomly chosen from a population of bricks whose mean length is 10 inches and whose standard deviation is \frac{1}{32} inch. Also, suppose that the mason, on the average, will make the mortar \frac{1}{2} inch thick, but the actual dimension varies from brick to brick, the standard deviation of the thickness being \frac{1}{16} inch. What is the standard deviation of the length of the first row of the wall?

    Thank you for your assistance.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by hasanbalkan View Post
    I would appreciate your help on the following problem:

    A mason is contracted to build a patio retaining wall. Plans call for the base of the wall to be a row of 50 10-inch bricks, each separated by \frac{1}{2}-inch-thick mortar. Suppose that the bricks used are randomly chosen from a population of bricks whose mean length is 10 inches and whose standard deviation is \frac{1}{32} inch. Also, suppose that the mason, on the average, will make the mortar \frac{1}{2} inch thick, but the actual dimension varies from brick to brick, the standard deviation of the thickness being \frac{1}{16} inch. What is the standard deviation of the length of the first row of the wall?

    Thank you for your assistance.
    The length of the wall is:

    L=(X_1+ ... + X_{50}) + (Y_1+ ... + Y_{49})

    Where the X's are RVs corresponding to the length of the 50 bricks and the Y's are RVs corresponding to the thickness of the mortar between consecutive bricks, and these are all independedntly distributed.

    The rest is just routine.

    CB
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Standard deviation word problem
    Posted in the Statistics Forum
    Replies: 8
    Last Post: October 17th 2010, 03:36 PM
  2. Standard Deviation problem/help
    Posted in the Statistics Forum
    Replies: 1
    Last Post: January 22nd 2010, 05:14 AM
  3. Problem with mean and standard deviation
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: July 29th 2009, 03:07 PM
  4. Standard deviation problem
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: April 21st 2009, 10:10 PM
  5. Standard deviation / mean problem
    Posted in the Statistics Forum
    Replies: 8
    Last Post: January 11th 2009, 09:24 PM

Search Tags


/mathhelpforum @mathhelpforum