<span>The correct answer is 4(4a+20b).
Hope i helped:P </span>
Hi there!
The total surface area (tsa) of a cone can be calculated with this formula :
TSA = (
× r × slant height) +
× r²
The "r" stands for "radius". The radius is equal to half the diameter, so in order to be able to use the formula, you'll need to divide the diameter by 2 to find the radius :
5 ÷ 2 = 2.5 = radius
Since the slang height is in meters, you'll need to transform it into centimeters in order to have both values in centimeters. To do so you'll need to use the cross product method :
1 m = 100 cm
4 m = x cm
(100 × 4) ÷ 1 = x cm
400 ÷ 1 = x cm
400 = x cm → The slant height is 400cm.
Now replace all the information in the formula and calculate everything :
TSA = (
× 2.5 × 400) + (
× 2.5²)
TSA = (
× 1,000) + (
× 6.25)
TSA ≅ 3,141.59 + 19.63
TSA ≅ 3,161.22 cm²
There you go! I really hope this helped, if there's anything just let me know! :)
Answer:

Step-by-step explanation:
The formula of a volume of a cylinder:

<em>r</em><em> - radius</em>
<em>H</em><em> - height</em>
<em />
We have a diameter <em>d = 8 → d = 2r → 2r = 8 → r = 4</em>
and <em>H = 12.</em>
<em></em>
Substitute:

Since x represents the number of students, and y represents the number of adult chaperones (and x does not include y), the best answer is A, that there are x = 50 students on the field trip, and they are accompanied by y = 5 chaperones.
Note the difference with choice c, which says that 50 is the total (45 students, 5 adults).
Hope this is clear and helpful :)