Q14. An analysis determined that approximately 99 percent of the observations of daily sales for a company were within the interval from $230,000 to $480,000 and that daily sales for the company were normally distributed. The mean daily sales and standard deviation of daffy sales, respectively, for the company were closest to:

Mean daily sales         stance deviation of day sales

A．   $351,450                      $41,667

B．   $351,450                      $83,333

C．   $355,000                      $41,557

D．   $355,000                      $83,333

答案和详解如下：

Q14,  C    07Mnduiar Level I, Vol.1, pp389 390  Study Session 3-9-9

Given that sales are normally distributed, the mean is centered in the interval

Mean = ($230,000+$480,000/2=$355,000

An interval including 99% of the observations extends three standard deviations either side of the mean. The standard deviation of daily sales = ($355,000-$230,000)/3=$41,667

c

Thanks

thx