Question

Find the value of x such that the data set has the given mean

100, 123, 105, 115, 110, x; mean 120

x=

Answer 1

The formula for mean is

all numbers added / how many numbers there are

Counting x, we have 6 terms.

(100 + 123 + 105 + 115 + 110 + x) / 6 = 120

Get rid of the denominator by multiplying 120 times 6.

100 + 123 + 105 + 115 + 110 + x = 720

Now, subtract everything on the left from 720 and isolate x.

100 + 123 + 105 + 115 + 110 = 553

720 - 553 = 167

x = 167