Answer: d. $2.38
Explanation:
Exponential decay function:
, where A = initial value
x= Time mperiod
b = multiplicative decay rate
As per given, we have
A = 38 dollars
b= 0.5
Amount after x years :

Then, at x= 4
Amount after 4 years :


Hence, the worth of electric can opener after 4 years = $2.38.
So, correct option is d. $2.38