Has a bad sandwich ever just kind of thrown your whole day off? Well, have we got a story for you...
|Social Studies||History Trivia|
to ship it in a sturdy tube. [Woman holding her trunk warmer]
The trunk warmer will fit perfectly in a tube with radius three and a height of five.
You think you have enough cardboard to make the tube yourself, but you're not totally sure... [The tube design drawn]
How much cardboard do you need?
Here are your potential answers: A cardboard shipping tube is the shape of a cylinder.
So to figure out this problem, we'll need to find the Surface Area of a Cylinder.
Well fortunately, there's a formula for finding the surface area of a cylinder. [The formula is written out]
But first, let's break down what the cylinder looks like when it's flattened... [Elephant sitting on the cylinder]
First, we'll need to find the area of each of those circles. [The circles are highlighted with arrows]
The formula for finding the area of a circle is pi times the radius squared.
Well our radius we know already is 3, so our formula will be pi times three squared. [The formula with the values inserted]
Three squared is nine.
Pi is approximately three-point-one-four,
so three-point-one-four times nine is twenty-eight-point-two-six. [The working is shown]
We have two circles, so we'll then need to double that number.
Twenty-eight-point-two-six times two is fifty-six-point-five-two.
So far this is easier than knitting that trunk warmer... [Old woman knitting in her rocking chair]
But we still have to find the area of the middle part of the cylinder...
… which is a rectangle when rolled flat. [The elephant sits on the cyclinder again]
To find this area, we'll need to multiply the height, which we know is five, by the
circumference of the circle. [The circumference of the circle is shown with an arrow]
This makes up the top and bottom edge of the rectangle.
We can find out what this is by using the simple formula two pi “r.”
Two times pi is approximately six-point-two-eight.
Six-point-two-eight times “r,” which is three in this case, is eighteen-point-eight-four. [The working is shown]
Now we just multiply that by the height, five, to get the surface area of the middle part
of the cylinder, which is ninety-four-point-two.
To get the total surface area, we just add our two numbers together.
Fifty-six-point-five-two plus ninety-four-point-two equals one-hundred-fifty-point-seven-two. [The total surface area formula is used]
So the answer is C.
Sounds like a lot of cardboard.
Good thing you've bought quite a few nasal hair trimmers over the years. [Pile of nasal hair trimmer boxes]