Question

Help with an algebra practice question?
Since 2005, the amount of money spent in restaurants in a certain country has increased at a rate of 7% each year. In 2005, about $300 billion was spent at restaurants. If the trend continues, about how much will be spent at restaurants in 2020?
How do I solve this? Do I need a graphing calculator to graph this exponential function as y= a * b^x? What would the equation look like? Steps please?

Answer 1

the equation would be y=5000(1.07)^x

Answer 2

not 5000, I meant 300,000,000,000, haha

Answer 3

2020 would be 15 years after 2005, so just plug in x=15

Answer 4

To graph you do not necessarily need a graphing calc...you could find points by plugging in x=1, x=2, etc...

Answer 5

So it would look like 300,000,000,000 * 1.07^15 ?

Answer 6

Exactly. Good work!

Answer 7

If you don't have a graphing calculator you can graph this equation at wolframalpha.com or by making a table of values and plotting points

Answer 8

Do i have to use all those zeros to get my answer?

Answer 9

could i add them in later?

Answer 10

Nope, you could just use 300. But remember, your answer will be in billions then

Answer 11

okay

Answer 12

If you get 405, that means 405,000,000,000

Answer 13

Okay so i did 1.07^15 * 300 and got 827.709462215. So, if rounded is my answer 828 billion?

Answer 14

(I was asked to round to the nearest whole number)

Answer 15

Not really. The nearest whole number would be to the nearest dollar, not nearest billion

Answer 16

That would just be my interpretation

Answer 17

so it would be $827,709,462,215?

Answer 18

That would be "rounded to the nearest whole number" yes

Answer 19

Rounded to the nearest billion dollars would be $828billion