How to Find the Missing Number of the Given Mean

How to Find the Missing Number of the Given Mean
••• IPGGutenbergUKLtd/iStock/GettyImages

The mean of a set of numbers is the average of those numbers. You can find the mean by adding the set of numbers and dividing by how many numbers are given. If you are given the mean and asked to find a missing number from the set, use a simple equation.

    Add up the numbers you know. The problem states a mean of 58 with this set of numbers: 43, 57, 63, 52 and ​x​. Assign the missing number a value of “​x​.” So add 43, 57, 63 and 52 to get 215.

    Set up your equation by adding 215 plus “​x​” (the missing number), divided by 5, the number of values given. Set that side of the equation equal to the mean, 58. So, your equation would look like this:


    Multiply each side by 5 since our goal is to get “​x​” by itself. This process cancels the 5 on the left side of the equation and gives you 290 on the right side (58 × 5). Now, your equation should look like this:

    215+x = 290

    Subtract 215 from each side as you continue to work to get “​x​” alone. This cancels out the 215 on the left side of the equation and gives you 75 on the right side. Now, your equation should show that ​x​ = 75. Therefore, the missing number is 75.

    Check the missing number by adding all the numbers together and dividing by 5.

    \frac{43+57+63+52+75}{5}=\frac{290}{5}= 58

    Which is the given mean.

Related Articles

How to Get the Average of Decimals
How to Calculate a Sigma Value
How to Calculate the Confidence Interval of the Mean
How to Calculate Statistical Mean
How to Solve for Range
How to Calculate the Root MSE in ANOVA
How to Calculate the Midpoint Between Two Numbers
How to Calculate Central Tendency
How to Compute a Population Mean
How do I Calculate the Geometric Mean on an HP 12C?
How to Determine the Assumed Mean
How to Calculate Standard Error of The Mean
How to Calculate Sides of a Triangle
How to Calculate SSE
How to Calculate a Temperature Range
How to Divide Rational Numbers
Define Mean for Math
How to Change Mixed Numbers Into Improper Fractions
How to Find the Missing Side of a Right Triangle
How to Add Parentheses to Make a Statement True