Answer:
18 should be added
Explanation:
So we have one 10 and one 11 in this data set, and we need to figure out which number we need to add to get a mean of 13
let's make this unknown number x
to find the mean, we add up all the values of the numbers on the data set, and divide it by how many numbers we have.
we have 3 numbers, and our numbers are 10, 11, and x. When we add 10, 11, and x together, and then divide by 3, the value is 13
as an equation we will have:
(10+11+x)/3=13
combining like terms in the numerator, it will be:
(21+x)/3=13
We need to solve this equation, and the denominator of 3 just makes harder to do that.
Clear the fraction by multiplying both sides by 3
21+x=39
subtract 21 from both sides
x=18
so that means that 18 should be added to the data set to get a mean of 13.
Hope this helps!