6. Records at a hospital show that a certain surgical procedure takes an average of 162.8 minutes with a standard deviation of 4.9 minutes. Assume that the data are approximately bell-shaped. (14 points) a) b) c) Between what two values will about 95% of the data fall? What percentage of surgical procedures took between 157.9 and 167.7 minutes? What percentage of surgical procedures took more than 153.0 minutes? d) What percentage of surgical procedures took between 172.6 and 177.5 minutes