Which of the following statements about interpreting standard deviation is true?

a. the empirical rule can't be applied unless the frequency distribution is mound-shaped and symmetric. chebyshev's rule can be applied to any data set, regardless of the shape of its frequency distribution.

b. chebyshev's rule can't be applied unless the frequency distribution is mound-shaped and symmetric. the empirical rule can be applied to any data set, regardless of the shape of its frequency distribution.

c. neither chebyshev's rule nor the emprical rule require any assumptions about the frequency distribution.

d. neither the empirical rule nor chebyshev's rule can be applied to data unless the frequency distribution is mound-shaped and symmetrical.

You are in charge of the customer service phone line with many employees. at the end of each phone callthe customers are asked to rate their service from 1 to 5 stars, with 5 being the best. you find the averagerating for 20 randomly selected employees and decide you want to improve the ratings so you require thoseemployees to go through a new training program. you then wait a week and find the new average rating foreach employee. the average change is an increase in 1.3 stars with a standard devation of .9 stars.(a) is this data paired or not paired? (b) what are the null and alternative hypothesis being tested? (c) what is the t-statistic you would use? write the general formula and the final calculation.(d) sketch a t-distribution, label your t-statistic and the probability you would be interested in: