Xuan T. answered • 05/26/20

Math Tutor for Elemtary/Middle/High School

Hi John,

The formula for mean/average is **m = sum of the terms/number of the terms**. Basically, you add all the numbers provided and divide it by how many of them.

So our terms are **48, 54, 51, 69, 64**. We are missing the last term, which the problem needs us to find, in order to meet the requirement of the **average 58 miles** per days, which is **m.**

Let's call the last term **x.**

m **= **sum of the terms/number of the terms

**58** = (**48 + 54 + 51 + 69 + 64 + x)/6**

We need to work backward the formula to find x.

Because (48 + 54 + 51 + 69 + 64 + x) *divided *by 6 gives us the m, which is 58, we will *multiply *58 by 6 to give us the *sum *of (48 + 54 + 51 + 69 + 64 + x)

**58 * 6 = 348**

So 348 is the sum of 48 + 54 + 51 + 69 + 64 + x. Let make it into an equation:

**48 + 54 + 51 + 69 + 64 + x = 348.** Now, simplify it by adding all the values except x.

**286 + x = 348.** Now what is left is to take 348 minus 286, which gives us **62**.

Let's check by plugging 62 as x into the mean formula.

(**48 + 54 + 51 + 69 + 64 + 62)/6 = m = 58**

Hope this helps!