Question

how many chest x - rays are needed to equal one year of exposure to natural background radiation?
0.1 to 0.3
more than 3
less than one
1 to 3
10 to 30

Explanation:

Natural background radiation exposure in a year is approximately 3 mSv. A chest X - ray typically delivers about 0.1 mSv. To find out how many chest X - rays equal one year of natural background radiation, we divide the annual natural background radiation dose by the dose per chest X - ray ($\frac{3}{0.1}=30$). But considering some approximations and variations, it is in the range of 10 - 30.

Answer:

10 to 30