Results 1 to 3 of 3

Math Help - Calculating grade

  1. #1
    Newbie
    Joined
    Jul 2005
    Posts
    12

    Unhappy word problem

    i am lost after i add 79,56,91,72 i divide by 4 after this is were i am stuck can you help me out i learn better if i can see the steps just once. here is the problem:

    A student has made a 79, 56, 91 and 72 on four tests. Determine the possible scores on the fifth test that will result in a 75 or higher average (assume an average cannot go higher than 100)…Hint: set up an inequality to calculate the grade if the average would be between 75 and 100.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Site Founder MathGuru's Avatar
    Joined
    Mar 2005
    From
    San Diego
    Posts
    478
    Awards
    1
    A student has made a 79, 56, 91 and 72 on four tests. Determine the possible scores on the fifth test that will result in a 75 or higher average

    The score on the fifth test we will call 'x'

    so the average after the fifth test will be:

    (79 + 56 + 91 + 72 + x)/5
    or

    (298 +x)/5

    or

    59.6 + x/5

    so what we want is:

    75 <= 59.6 + x/5

    15.4 <= x/5

    77 <= x

    In order to get at least a 75, the student needs to score a 77 or higher.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Joined
    Apr 2005
    Posts
    1,631
    Here is one way.

    If there are 5 test in total, then the average grade is the sum of the 5 grades divided by 5.

    75 <= (79 +56 +91 +72 +x)/5 <= 100
    75 <= (298+x)/5 <= 100
    Clear the fraction, multiply all sides by 5,
    375 <= 298 +x <= 500
    Isolate the x, subtract 298 from all sides,
    77 <= x <= 202

    That means on the 5th test, the student must score anywhere between 77 and 202.

    Can a grade or test score be more than 100?
    If not, then the 5th grade should be anywhere from 77 to 100.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Challenging grade 6 question or grade 9 ?
    Posted in the Algebra Forum
    Replies: 2
    Last Post: June 24th 2010, 11:04 AM
  2. Replies: 1
    Last Post: June 6th 2010, 10:51 PM
  3. Course Grade
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 26th 2009, 08:42 PM
  4. What grade do I need?
    Posted in the Math Topics Forum
    Replies: 5
    Last Post: May 2nd 2007, 07:34 PM
  5. calculating grade
    Posted in the Algebra Forum
    Replies: 7
    Last Post: January 14th 2006, 01:26 AM

Search Tags


/mathhelpforum @mathhelpforum