The mean of a data is 52.4 and the standard deviation is 11.8.what percent of the data is between 40.6 and 64.2?
a.50%
b.68%
c.95%
d.99.7%

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.