The first raise was a 25% increase, while the second raise was a 32% increase so there was a 7% increase from the first raise to the second one.
The formula for this is

. If the diameter is 8 the radius is 4, so filling in accordingly we have

and

which is

and when you multiply in 3.14 you get that A = 401.92 or B above.
The number of ants in his farm after 12 weeks is 218.
Step-by-step explanation:
Step 1:
It is given that there are 15 ants initially and the ant population increases by 25% each week.
This is an exponential rate of increase that can be modeled by the following equation:
Number of ants after n weeks = Initial number of ants * 
Step 2:
Rate of increase = 25% = 25 / 100 = 0.25
Number of weeks = 12
Number of ants after 12 weeks = 15*
= 218.27 (rounded off to 218)
Step 3:
Answer:
The number of ants in his farm after 12 weeks is 218.
Answer: 3 days
Step-by-step explanation: It would take 3 days for seven hens to 7 lay eggs because each hen lays an egg each day.
1 hen/1 egg = 3 days
7 hens/7 days = 14 eggs
7 hens/3 days = 7 eggs
You are dividing a number (x) by three and then subtracting 1 like this. (x/3)-1