Mark works at a clothing store and earns a 20% commission on his total sales. last month, mark sold $1,500 in clothing total sales. what was his commission last month?

Do one of the following, as appropriate: (a) find the critical value z subscript alpha divided by 2 , (b) find the critical value t subscript alpha divided by 2 . 99%; nequals 17; sigma is unknown; population appears to be normally distributed.