Question

6. In a toy factory, 200 wooden closed cylinders of diameter 35 mm and height 7 cm have to be painted. What is the total surface area, in cm², that needs to be painted? (Take pi to be 3.142.)
7. A tank in the shape of a cylinder of diameter 2.4 m and height 6.4 m contains oil to the brim. Find the number of complete cylindrical containers of base radius 8.2 cm and height 28 cm which can be filled by the oil in the tank.

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Answer 1

Answer:

6) About 19,244.75 square centimeters.

7)  About 4895 containers.

Step-by-step explanation:

Question 6)

We need to paint 200 wooden closed cylinders of diameter 35 mm and height 7 cm. And we want to find the total surface area that needs to be painted.

First, since the diameter is 35 mm, this is equivalent to 3.5 cm.

The radius is half the diameter, so the radius of each cylinder is 1.75 cm.

Recall that the surface area of a cylinder is given by the formula:

$\displaystyle \text{SA}=2\pi r^2+ 2\pi rh$

Where r is the radius and h is the height.

Therefore, the surface area of a single cylinder will be:

$\displasytyle \text{SA}=2(3.142)(1.75)^2+2(3.142)(1.75)(7) = 96.22375\text{ cm}^2$

Then the total surface area for 200 cylinders will be:

$\displaystyle \text{SA}_{\text{total}}=200(96.22375)=19244.75\text{ cm}^2$

Question 7)

We know that the tank has a diameter of 2.4 m and a height of 6.4 m.

Since its diamter is 2.4 m, then its radius is 1.2 m.

Find the total volume of the tank. The volume for a cylinder is given by:

$\displaystyle V=\pi r^2h$

Since r = 1.2 and h = 6.4:

$\displaystyle V=(3.142)(1.2)^2(6.4)=28.956672\text{ m}^3$

Each container has a base radius of 8.2 cm and a height of 28 cm.

So, the radius of each container is 0.082 m and the height is 0.28 m.

Then the volume of each container is:

$\displaystyle V=(3.142)(0.082)^2(0.28)=0.005915506\text{ m}^3$

Then to find the number of containers that can be filled by the tank, we can divide the two values. Hence:

$\displaystyle C=\frac{28.956672}{0.005915506}=4895.045466\approx 4895$

Thus, approximately 4895 containers can be filled.

Answer 2

Answer:

6) About 19,244.75 square centimeters.

7)  About 4895 containers.

Step-by-step explanation:

Question 6)

We need to paint 200 wooden closed cylinders of diameter 35 mm and height 7 cm. And we want to find the total surface area that needs to be painted.

First, since the diameter is 35 mm, this is equivalent to 3.5 cm.

The radius is half the diameter, so the radius of each cylinder is 1.75 cm.

Recall that the surface area of a cylinder is given by the formula:

Where r is the radius and h is the height.

Therefore, the surface area of a single cylinder will be:

Then the total surface area for 200 cylinders will be:

Question 7)

We know that the tank has a diameter of 2.4 m and a height of 6.4 m.

Since its diamter is 2.4 m, then its radius is 1.2 m.

Find the total volume of the tank. The volume for a cylinder is given by:

Since r = 1.2 and h = 6.4:

Each container has a base radius of 8.2 cm and a height of 28 cm.

So, the radius of each container is 0.082 m and the height is 0.28 m.

Then the volume of each container is:

Then to find the number of containers that can be filled by the tank, we can divide the two values. Hence: