If a = {x : 1 < x < 9} ; b = {x : 0 < x < 9} ; C = {x : 2 x < 9} and a, b, c U, what are the elements in U?
If 7 is subtracted from twice a certain number x, the result is at most 5. What is the range of the number?
Find the standard deviation of the numbers 6, 9, 10, 8 and 7
