Question

Geoff planted dahlias in his garden. Daliahs have bulbs that divide and reproduce underground. In the first year, Geoff's garden produced 6 bulbs. In the second year, it produced 12 bulbs, and in the third year, it produced 24 bulbs. If this pattern continues, how many bulbs should Geoff expect in the eighth year?
A)48 bulbs
B)384 bulbs
C)768 bulbs
D)1,536
I think it's B?

Answer 1

The answer is C because your times each number by 2 6 times 2 is 12, 12 times 2 is 24, 24 times 2 is 48 and you do it 8 times until you get your answer which is 768 bulbs

Answer 2

This is a geometric sequence of the form:

a(n)=ar^(n-1), a=initial term, r=common ratio, n=term number

The common ratio, r, is the defining characteristic of geometric sequences.  It is the value found when dividing each term by the previous term.  In this case:

r=24/12=12/6=2 and we see that the initial value is 6 so

a(n)=6(2)^(n-1) so in the eighth year:

a(8)=6(2^7)

a(8)=768

So after eight years there will be 768 bulbs.