Question

The total cost of an item including sales tax is directly proportional to its price. If the total cost of a $32 item is $33.60 , what is the total cost on a $55 item

Answer 1

Let the total cost of the item be represented by C and the price be represented by P, then given that the total cost of an item including sales tax is directly proportional to its price, thus

$C\propto P \\ \\ \Rightarrow C=kP$

where k is a constant.

Given that the total cost of a $32 item is $33.60, thus

$33.60=32k \\ \\ \Rightarrow k= \frac{33.60}{32} =1.05$

Therefore, the total cost on a $55 item is given by

$C=1.05\times55=\ 57.75$