Question

A pyramid of cans has 52 cans on the bottom row and 1 can on the top row. If it took 477 cans to build the pyramid how many rows are in the pyramid?

Answer 1

this is an arithmetic progression with

first term,a =top row

last term, l = bottom row and

n is no. of rows

sum of arithmetic progression with a,l is

n(a+l)/2

given

a=1

l=52

sum =477

so

n/2(a+l)= 477

n(a+l) =477×2

n(1+52) =477×2

n = 477×2/3 =318