25. A supermarket soup can display consists of 5 levels of stacked cans. The figure below shows an overhead view of the top level of cans (circles shaded and with solid borders) and the level of cans below it (circles with dashed borders). In the display, each level has 4 more cans than the level above it. How many cans are in the display?
Your Answer is
Correct Answer is E
Explanation
The formula for summing the arithmetic sequence is (first item + last item)×number of items÷2. The top layer is 4×5=20 cans, and the bottom layer is 20+4×4=36 cans. (20+36)×5÷2=140. Choose E.