Mean Math Example 2

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Example 2

medium
A student scored 72,85,90,6872, 85, 90, 68, and 9595 on five tests. What score does she need on the sixth test to achieve a mean of 8585?

Solution

  1. 1
    Let the unknown score be xx. The desired mean is 8585 over 66 tests.
  2. 2
    Set up the equation: 72+85+90+68+95+x6=85\frac{72 + 85 + 90 + 68 + 95 + x}{6} = 85.
  3. 3
    Sum the known scores: 72+85+90+68+95=41072 + 85 + 90 + 68 + 95 = 410.
  4. 4
    Solve: 410+x=85×6=510410 + x = 85 \times 6 = 510, so x=100x = 100.

Answer

x=100x = 100
Working backwards from a desired mean involves setting up an equation where the total sum equals the mean times the count. This technique is useful in goal-setting problems.

About Mean

The arithmetic mean (average) of a data set is the sum of all values divided by the number of values.

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More Mean Examples

Example 1 easy

Find the arithmetic mean of the data set: [formula].

Example 3 easy

Find the mean of [formula].

Example 4 medium

Five quiz scores have a mean of [formula]. Four of the scores are [formula], [formula], [formula], a

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