Question

Nia plans to put enough money in the bank each week for 100 weeks so that the amount in the bank is always proportional to the week number. On week 8, she had $20.00. On week 12, she had $30.00. How much money will be in the savings account on week 100? A line graph titled Nia's Savings has week number on the x-axis, and Amount in Savings on the y-axis. At week 8 she had 20 dollars, at week 12 she had 30 dollars.

Answer 1

On week 100 she has $250.

Explanation:

A proportional relation has the form

y = kx

Let x = week number and y = amount of money in the account.

We use one of the known times and mounts to find the value of k.

At week 8 she had $20.00, so for x = 8, y = 20.

y = kx

20 = k * 8

k = 20/8

k = 2.5

The proportional relation is

y = 2.5x

Now for any number of weeks, x, you can find the amount of money, y, using the equation above.

On week 100, x = 100.

y = 2.5x

y = 2.5(100)

y = 250

Answer: On week 100 she has $250.

Answer 2

$250

Explanation:

8=20

12=30

So waht you do is you know that 4 weeks is $10 so 10 / 4 = 2.5 and 2.50 x 100 = 250.