Question : You have collected a large amount of data in the last 3 weeks. Sampling was accomplished from a population set of over 1000 data sets. The mean for the data set is 50 and a standard deviation of 10. Which of the following is true ?

(a) A value of 11 is within one standard deviation of the mean

(b) 41, 45 and 109 are within the range of values which could be expected about 68% of the time

(c) 38 and 62 are within two-sigma limits 95.45% of the time

(d) Values of 30 and 80 fall within the three-sigma limits