The diagram shows a child's toy.

Question

The diagram shows a child's toy. The toy is made from a cone on top of a hemisphere. The cone and hemisphere each have radius 7 cm. The total height of the toy is 22cm. Work out the volume of the toy. Give your answer correct to 3 significant figures.

Answer 1

V of a sphere = 4/3 * π  * r³  And we'll need to divide this by two since we have half of a sphere.

V of a cone = 1/3 * π *r² * h

r = 7 cm

Total height is 22cm. remove 7 for the hemisphere, and we get 15 for the cone's h.

 

hemisphere volume:

4 / 3 / 2 * 3.14 * 7³ → 2 / 3 * 3.14 * 343 = 718.01333....

 

Cone volume:

1 / 3 * 3.14 * 7² → 49 / 3 * 3.14 = 51.28666....

 

718.01333 + 51.28666 = 769.30

 

Since we need only three significant figures, that means our final answer is 769 cm³