Answer:
51
Step-by-step explanation:
The mean is obtained by adding up the values in the data set and then divide by the number of values that you added:
[tex]\bar X=\sum{X_i}\\[/tex]
Given our mean as 11.5 and n=4:
[tex]\bar X=\frac{1}{n}\sum{X_i}\\\\\\\\\therefore\sum{X_i}\\=11.5\times 4=46[/tex]
#Knowing our sum as 65, we can obtain x by subtracting sum of known values from 65:
[tex]x=46-(12.5+-10+-7.5)\\=51[/tex]
Hence, the value of x is 51
