MATH SOLVE

4 months ago

Q:
# A grocer stacks oranges in a four-sided pyramid that is 7 layers high. How many oranges are in the pile? A.504 B.840 C.140 D.120

Accepted Solution

A:

Answer:Option C. 140Step-by-step explanation:Base of a pyramid which has four triangular sides is four sided.If pyramid contains seven layers of oranges then the layer at the bottom will have 7 oranges.Since base is a square then other side of the square base will have the same number of oranges = 7.Therefore number of oranges at the first layer will be = 7×7Similarly other layers above this layer will have the same sequence 6×6, 5×5, 4×4, 3×3, 2×2, 1×1Therefore total number of oranges = 7×7 + 6×6 + 5×5 + 4×4 + 3×3 + 2×2 + 1×1 = 49 + 36 + 25 + 16 + 9 + 4 + 1 = 140Option C. 140 is the answer.