Question

Mike forgot to replace the cap on a bottle of room freshener. The room freshener began to evaporate at the rate of 15% per day. If the original amount of room freshener in the bottle was 40 grams, which of the following graphs best represents the amount of room freshener f(x) that would remain in the bottle after x days?

Answer 1

Percentages are out of 100. So we'll multiply by 0.85 to represent the 15%

To find the y points on the graph we can use f(x) = $0.85^x*40$

We'll input 1-5 for x to find y:

1:  $0.85^1=0.85*40=34$
2: $0.85^2=0.7225*40=28.9$
3: $0.85^3=0.614125*40=24.57$
4: $0.85^4= 0.52200625*40=20.88$
5: $0.85^5=0.443705312*40=17.75$

Therefore the answer is a graph of exponential function going down from left to right in quadrant 1 through the point 0, 40 and approaching the x-axis.