Answer:
The time will be 25 minutes in which snowball be completely melted.
Step-by-step explanation:
Given : The rate of change of the volume of a snowball that is melting is proportional to the surface area of the snowball. Suppose the snowball is perfectly spherical. 
Then the volume (in centimeters cubed) of a ball of radius r centimeters is 
The surface area is 
Set up the differential equation for how r is changing. Then, suppose that at time t = 0 minutes, the radius is 10 centimeters. After 5 minutes, the radius is 8 centimeters. 
To find : At what time t will the snowball be completely melted?
Solution :
Using given condition,

 ....(1)
 ....(1)


Substitute in (1),
 
 
 
 
 
 
Now, t=0 , r=10 
So,  
 
 
 
i.e.  
 
After 5 minutes, t=5 , r=8
 
 
 
 
 
 
The equation form is  
 
The snowball be completely melted means radius became zero.
 
 
 
 
 
 
 
 
The time will be 25 minutes in which snowball be completely melted.