Background radiation from cosmic rays and radioactive nuclei in our surroundings is about 0.13 rem/year. Suppose we assume this all comes from cosmic rays which have an RBE factor of 1.0. The RBE factor for the most dangerous types of radiation is 20. How many rads of the most dangerous radiation could a 100-year-old person have been exposed to in her lifetime without having gone over the recommended limit of 0.5 rem/year?
A) 0.37
B) 0.50
C) 1.85
D) 13
E) 37

Question

Quizplus · Accepted Answer

We know that the recommended limit is 0.5 rem/year, and the background radiation is 0.13 rem/year. This means a person can be exposed to 0.37 rem/year of the most dangerous radiation without exceeding the recommended limit (0.5 - 0.13 = 0.37).

We also know that the RBE factor for the most dangerous radiation is 20, which means that 1 rad of the most dangerous radiation is equivalent to 20 rads of background radiation.

Therefore, to determine how many rads of the most dangerous radiation a person can be exposed to without exceeding the recommended limit, we can use the following equation:

0.37 rem/year x (1 rad / 20 rem) = 0.0185 rads/year

Multiplying this by the person's age, 100 years, we get:

0.0185 rads/year x 100 years = 1.85 rads

So the person could have been exposed to a total of 1.85 rads of the most dangerous radiation in their lifetime without exceeding the recommended limit. Thus, the best answer choice is C) 1.85.

Background Radiation from Cosmic Rays and Radioactive Nuclei in Our