So the best and correct answer is C because this is how you do it The surface area of the cone has formula
pi * radius * ( radius + sqrt ( height^2 + radius^2)) =
pi * radius^2 + pi * radius * sqrt( height^2 + radius^2)
However, this includes the base of the cone and the hats do NOT have
that. "The hats are shaped like a cone with NO BASE", says the 3rd sentence.
So the formula becomes pi * radius * sqrt( height^2 + radius^2)
diameter = 16
radius = 8
height = 9
The surface area of ONE of the hats is pi * 8 * sqrt( 9^2 + 8^2)
= pi * 8 * sqrt( 81+64)
= pi * 8 * sqrt(145)
302.63828053.....
21 of them is 21 * 302... = 6355.40689112841343251026086.....
C $1.00
because 1/3 of 15 coins are 5 dimes
15 - 5 = 10 nickels
10 + 5 = 15 coins.
5 dimes= .50 cents
10 nickels= . 50 cents
.50 + .50 = $1.00
$1.00 is C.
*Hope this helped :)
The Four basic Mathematical Operations are:
•Addition
•Subtraction
•Multiplication
•Division
