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 2
Six months of darkness at the North Pole begins when the Sun is at the
a. winter solstice.
b. summer solstice.
c. autumnal equinox.
d. vernal equinox.