The average of 8 people in a golf club is 44. A ninth person joins the club and the new average of the golf club is 47. What is the age, in years, of the ninth person?
Suppose x is the total age before the ninth person joins. x/8=44 then the new persons age is a then x+a/9=47 so you subsitute x=352 then (352+a)/9=47 then 352+a=393 so we find a=41
