Question

New grass seeds grow rapidly. A grass seed has grown to 12 millimeters tall. Tomorrow it will be 23 inches tall, the next day it will be 34 inches tall, and on the next day it will be 45 inches tall. Write a rule to represent the height of the bean plant as an arithmetic sequence. How tall will the plant be in 15 days.
Options are:
A(n)=16+(n-1)11;194 inches
A(n)=12+(n-1)11;166 inches
A(n)=13n;195 inches
A(n)=12n;180 inches

Please explain how to know which one is the answer.

Answer 1

Ok so on day one we start off with the grass seed grown 12 mm
n represents the amount of day so let n=1 and see which equation equals 12 when n=1

Answer 2

So it's D? I'm not sure how that worked out.

Answer 3

Well there are 2 equations that equal 12
D and B
Take a look at B
Next on day 2 it is 23 inches tall
So let n=2 and plug that in to equation B and D and see which one equals 23

Answer 4

Don't they both equal 24 when doing that? Also, I think since 180 divided by 12 is 15, it could be right. and where are you coming up n values?

Answer 5

Ok n represents the days
So on day 1 the grass seed grows 12 mm so when n=1 the equation must equal 12
On day 2 the grass seed will be 23 mm so when n=2 the equation equals 23
On day 3 the grass seed will be 34 mm so when n=3 the equation will equal 34
and so forth.
Now lemme show you what happens when you plug in n=2 into B and D

Equation B
12+(2-1)11
12+11=23

Equation D
12(2)=24

See the difference between the 2 equations?

Answer 6

I think I get it now. So B is the right answer?

Answer 7

Yes :)

Answer 8

In this event its basically trial and error. Depending on the info given sometimes you need to create the equation or series formula

Answer 9

Thank you! It's all so clear now.

Answer 10

You can always ping me if ya need help with another one

Answer 11

I sure will.