Question

A computer purchased for $1,050 loses 19% of its value every year.

Answer 1

Answer:

A) a = 1050 and b = 0.81

B) 3.3

Step-by-step explanation:

Original price of the computer = $ 1050

Rate of decrease in price = r = 19%

This means, every year the price of the computer will be 19% lesser than the previous year. In other words we can say that after a year, the price of the computer will be 81% of the price of the previous year.

Part A)

The exponential model is:

$v(t)=a(b)^{t}$

Here, a indicates the original price of the computer i.e. the price at time t = 0. So for the given case the value of a will be 1050

b represents the multiplicative rate of change i.e. the percentage that would be multiplied to the price of previous year to get the new price. For this case b would be 81% or 0.81

So, a = 1050 and b = 0.81

The exponential model would be:

$v(t)=1050(0.81)^{t}$

Part B)

We have to find after how many years, the worth of the computer will be reduced to half. This means we have the value of v which is 1050/2 = $ 525

Using the exponential model, we get:

$525=1050(0.81)^{t}\\\\ 0.5=(0.81)^{t}$

Taking log of both sides:

$log(0.5)=log(0.81)^{t}\\\\ log(0.5)=t \times log(0.81)\\\\ t = \frac{log(0.5)}{log(0.81)}\\\\ t = 3.3$

Thus, after 3.3 years the worth of computer will be half of its original price.