a grocery store display consists of cases of soda. there are 15 cases at the base, and 1 case at the top. if there are 15 rows, how many cases are needed for the entire display? a) 180 b)30 c)130 d)15

Question

a grocery store display consists of cases of soda. there are 15 cases at the base, and 1 case at the top. if there are 15 rows, how many cases are needed for the entire display?                               a) 180 b)30 c)130 d)15

Reiny · Answer

looks like an arithmetic series sum of terms of AS = (n/2)(first + last) = (15/2)(15+1) = 120 check: 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15 = 120