Question
a grocery store display consists of cases of soda. there are 15 cases at the base, & 1case 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
Answers
Steve
What you have is 1+2+3+...+15
That is just
(1+15) + (2+14) + ...
There are 7 pairs of 16 + 8 in the middle:
112+8 = 120
1+2+...+n = n(n+1)/2 = 15(16)/2 = 120
That is just
(1+15) + (2+14) + ...
There are 7 pairs of 16 + 8 in the middle:
112+8 = 120
1+2+...+n = n(n+1)/2 = 15(16)/2 = 120