Question

question 24 (mandatory) (1 point) a bicycle loses its value each month after it is purchased. its value as a function of time, in months, is modelled by $v(m)=2200(0.98)^m$. in which month after it is purchased does the bicycles worth fall below $1500? a) 15 b) 16 c) 18 d) 17

Explanation:

Step1: Set up the inequality

We want to find $m$ such that $V(m)=2200(0.98)^m<1500$. So, we have the inequality $2200(0.98)^m < 1500$. First, divide both sides by 2200: $(0.98)^m<\frac{1500}{2200}=\frac{15}{22}$.

Step2: Take the natural - logarithm of both sides

Taking the natural - logarithm of both sides of $(0.98)^m<\frac{15}{22}$, we get $m\ln(0.98)<\ln(\frac{15}{22})$. Since $\ln(0.98)<0$, when we divide both sides of the inequality by $\ln(0.98)$, the direction of the inequality sign changes. So, $m>\frac{\ln(\frac{15}{22})}{\ln(0.98)}$.

Step3: Calculate the value of $m$

We know that $\ln(\frac{15}{22})\approx\ln(15)-\ln(22)\approx2.7081 - 3.0910=- 0.3829$ and $\ln(0.98)\approx - 0.0202$. Then $m>\frac{-0.3829}{-0.0202}\approx18.955$.

Answer:

c) 18