Answer: 
Step-by-step explanation:
Given
Population of dust particle doubles every 30 minutes
If the initial sample is 21 grams
The model to predict the population will be

Where t=time in hours
A day has 24 hours . So, for 2 days time is 48 hours
Population is given by
Multiply 8 by 4 and that will give you 32 then add 9 and you get 41 so the answer is 41 years old
Answer:
$2.40 or $77.55
Step-by-step explanation:
I don't know if you are asking for how much off or what, so I'm doing both
First, we have to find how much we have to take off or what is 30% of 79.95 so our equation is:
79.95 x 0.03 = 2.40
So 30% of 79.95 is $2.40
To find how much our new price sale is, we have to take that $2.40 off so our equation is:
79.95 - 2.4 = 77.55
So our discount price is $77.55
hope this helps:)
Answer:
im sorry, the answer to what?
Answer:
12.5 pi or 39.26990
Step-by-step explanation:
First we can find the radius, which is half the diameter, 5 feet. To find the area of a semi-circle we would find the area of the circle and then divide by 2:

We can substitute what we have:

This gives us:
12.5 pi or 39.26990(Not sure what format you need it in)