In 1974, there were 17 countries that had at least One nuclear reactor installed and operating. The mean and standard deviation of the numbers of nuclear power reactors for 17 countries are 7.5 and 11.1 respectively. A. The USA had 42 operating nuclear power reactors. Do you think any country had more? Why? B. Do you think the data are symmetric or skewed? Solution Z =(42-7.5)/(11.1/17) = 12.815 P(Z > 12.815) =0 So, no country had more. symmetrical.