If the dimensions of the following cylinder are doubled, what factor will the surface area change by? radius: 8 in height: 6in a. 2 b. 4 c. 6 d. 8

To solve this problem you must apply the proccedure shown below:
 1. You have that the radius and the height of the cylinder are:
 
 2. So, you must calculate the area:
 
 3. Substitute the values into the formula:
 
 4. When the radius and the height are doubled, you obtain:
 
 5. The factor is:
 
 The answer is: B. 

Ithink it should be 55.