Answer:
D
Step-by-step explanation:
Volume of cylinder:
V = πr²h
The desired volume is 1 Liter = 1000 cm³
1000 = πr²h
h = 1000/πr²
Surface area of cylinder:
S.A = 2πr² + 2πr²h
We substitute the value of h from the first equation:
S.A = 2πr² + 2πr(1/πr²)
S.A = 2πr² + 2/r
Now, to minimize surface area, we differentiate the expression with respect to r and equate to 0.
0 = 4πr - 1000/r²
4πr³ - 1000 = 0
r = 4.3 cm
h = 17.2 cm
x= 1/4 , -9/4
when you set the function to equal to zero you will get these values
Answer:
36 cups
Step-by-step explanation:
every 20 minutes you make 12 cups. 20×3=60, which is 1 hour. You will meed to make 3 pots of coffee that are 12 cups each, 3×12=36
