Step-by-step explanation:
We have given that,
The inner radius of a bicycle wheel is 12 inches.
It is required to find the expression to find the inside circumference of this wheel.
The outer surface of the wheel is equal to its circumference. It is given by :

r is radius of wheel

This is the required explanation.
Answer:
C
Step-by-step explanation:
You move to the right, so the exponent is gonna be negative.
1.21 * 10-²
Solve
hmmm
half life
well, 120 to 60 is half
60=120e^(-0.00043t)
solve for t
divide both sides by 120
1/2=e^(-0.00043t)
take ln of both sides
ln(1/2)=-0.00043t
divide both sides by -0.00043
ln(1/2)/-0.00043=t
t≈1611.97 years
about 1612 years
I think it’s this but I’m not sure