What is the missing number in the data set 15,17,28,30 if the mean is 23

15+17+28+30=90, if theres another number than there r 5 total numbers, 23*5=115, 115-90=25, so 25

Mean is add the numbers and divide the result by how many numbers there are

mean=23

1 missing number which is x

5 numbers including missing one

(15+17+28+30+x) / 5=23

solve for x

multiply both sides by 5

15+17+28+30+x=115

add like terms

90+x=115

subtract 90

x=25

the missing number is 25