Answer:
D
Step-by-step explanation:
Use the formula for the SA of a hemisphere.

Now we can find the radius of the hemisphere, which is 15.
Then, we can square that and multiply it by 2 to get 450.
Now, let's use the formula for the Volume of a hemisphere.

Now we can cube 15 and multiply it by 2 to get 6750.
Then we can divide this number by 3.
2250.
So the answer is D.
Answer:
D
Step-by-step explanation:
Answer:

Step-by-step explanation:
The relationship between A, the area of the glacier in square kilometers, and t, the number of years the glacier has been melting, is modeled by the equation.:

We want to determine the value of t for which the area, A(t)=15 square kilometers.

Therefore, the time for which the area will be 15 sqyare kilometers is:
-20 ln(1/3) years.
Answer:
<em>20 boys </em>
Step-by-step explanation:
b = 2g
100% - 20% = 80%
80% ÷ 2 = 40% = 0.4
0.4g = 4 ⇒ g = 4 ÷ 0.4 = 10
b = 2 × 10 = 20
There are 10girls and <em>20 boys</em> study in the class.