Penn stacks all of his snowballs in a square pyramid...... Which could not be the number of snowballs penn has?

Question

asked Mar 2, 2020 234k views

2 Answers

Russell Zornes · Answer 1 · 2020-03-09T12:20:24+0000

Answer:

The correct option is B.

Explanation:

The number of snowballs in n layers of square pyramid is given by

P(n)=P(n-1)+n^2

P(1)=P(1-1)+1^2

P(1)=P(0)+1=1

P(2)=P(2-1)+2^2

$P(2)=P(1)+4\Rightarrow 1+4=5$

P(3)=P(3-1)+3^2

$P(3)=P(2)+9\Rightarrow 5+9=14$

P(4)=P(4-1)+4^2

$P(4)=P(3)+16\Rightarrow 14+16=30$

P(5)=P(5-1)+5^2

$P(5)=P(4)+25\Rightarrow 30+25=55$

The values of P(n) are 1, 5, 14, 30, 55 ,....

25 could not be the number of snowballs penn has.

Therefore the correct option is B.