Aimee packs ice cream into an ice cream cone. She then

puts a perfect hemisphere of ice cream on top of the cone
that has a diameter of 5 cm.
What is the volume of the hemisphere (half of a sphere),
rounded to the nearest hundredth?
*Show all steps to earn full credit.

1 answer

To find the volume of a hemisphere, we start by using the formula for the volume of a full sphere and then divide it by 2.

The formula for the volume \( V \) of a sphere is:

\[ V = \frac{4}{3} \pi r^3 \]

where \( r \) is the radius of the sphere.

Step 1: Find the radius of the hemisphere

Given that the diameter of the hemisphere is 5 cm, we can find the radius \( r \):

\[ r = \frac{\text{diameter}}{2} = \frac{5 \text{ cm}}{2} = 2.5 \text{ cm} \]

Step 2: Calculate the volume of the hemisphere

Since a hemisphere is half of a sphere, the formula for the volume of a hemisphere \( V_h \) is:

\[ V_h = \frac{1}{2} \times V_{\text{sphere}} = \frac{1}{2} \times \frac{4}{3} \pi r^3 \]

Now substituting \( r \):

\[ V_h = \frac{1}{2} \times \frac{4}{3} \pi (2.5)^3 \]

Step 3: Calculate \( (2.5)^3 \)

Calculating \( (2.5)^3 \):

\[ (2.5)^3 = 2.5 \times 2.5 \times 2.5 \]

Calculating step by step:

  1. \( 2.5 \times 2.5 = 6.25 \)
  2. \( 6.25 \times 2.5 = 15.625 \)

So,

\[ (2.5)^3 = 15.625 \]

Step 4: Substitute back into the volume formula

Now, substitute back into the volume formula:

\[ V_h = \frac{1}{2} \times \frac{4}{3} \pi (15.625) \]

\[ = \frac{4 \times 15.625}{6} \pi \]

Calculating \( 4 \times 15.625 \):

\[ 4 \times 15.625 = 62.5 \]

So, we now have:

\[ V_h = \frac{62.5}{6} \pi \]

Step 5: Calculate \( \frac{62.5}{6} \)

Calculating \( \frac{62.5}{6} \):

\[ 62.5 \div 6 \approx 10.41667 \]

Step 6: Final volume calculation

Now substituting back to find the volume:

\[ V_h \approx 10.41667 \pi \]

Using \( \pi \approx 3.14159 \):

\[ V_h \approx 10.41667 \times 3.14159 \approx 32.749 \]

Step 7: Round to the nearest hundredth

Rounding \( 32.749 \) to the nearest hundredth:

\[ V_h \approx 32.75 \text{ cm}^3 \]

Final Answer

Therefore, the volume of the hemisphere rounded to the nearest hundredth is:

\[ \boxed{32.75} \text{ cm}^3 \]