Plzzz at the bookstore checkout you watch as the register rings up your purchases and coupons the prices were as follows $1.85 $8.56 $6.30 $2.73 $5.25 $4.09 $7.95 -$0.85 (coupon) -$2.10 (coupon)

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.