Osteoporosis is a condition in which the bones become brittle due to a loss of minerals. To diagnosis osteoporosis, we look at bone mineral density (BMD). BMD is usually reported in standardized form, and the standardization is based on a population of healthy young adults. The WHO definition of osteoporosis is a BMD 2.5 standard deviations below the mean for young adults. BMD measurements in a population of people similar in age and sex roughly follow a normal distribution. a. What percent of healthy young adults have osteoporosis by the WHO criterion?

b. Women aged 70-79 ae of course not young adults, and their mean BMD is about -2 standard deviations on the standard scale for young adults. What percent of this older population has osteoporosis? 4. Energy consumed in the U.S. is classified as coming from one of three sources: fossil fuels, nuclear and electric power, and renewable energy. In 2018, the energy from these three sources was 81.0, 8.4, and 11.5 quadrillion Btu, respectively. In 2008, the corresponding