Hello!

Solve for the distance by solving for the circumference of the wheels:
C = 2rπ
C = 2(8.5)(π)
C = 17π
The wheels make 15 rotations, so multiply the circumference by 15:
17π × 15 = 255π or ≈ 800.7 inches
This is a relatively easy half life calculation.
After one half-life period, half of the isotope remains.
After two half-life periods, one quarter of the isotope remains.
That being the case, we see this will take 2 half-life periods or 6 days.
Answer:
A C and E
Step-by-step explanation:
Answer:
D
Step-by-step explanation:
red blood cell = 0.000009 = 9 × 
cold virus = 0.0000003 = 3 × 
Divide diameter of red blood cell by diameter of cold virus

= 3 × 
= 3 
= 3 × 10² → D