BSAD 210- BUSINESS STATISTICS
SECTION: 32357
TEST 3- TAKE HOME.
DUE BY THURSDAY APRIL 2, 2020 AT 11:59 PM
Name:
1. According to an IRS study, it takes an average of 330
minutes for taxpayers to prepare, copy, and
electronically file a 1040 tax form. A consumer
watchdog agency selects a random sample of 40
taxpayers and finds the standard deviation of the time
to prepare, copy and electronically file form 1040 is 80
minutes.
a. What assumption or assumptions do you need to
make about the shape of the population?
If we assume this sample is normal distribution than this sample must be symmetric and bell-shaped.
b. What is the standard error of the mean in this
example?
SE (x)= S/Square root of n. 80/square root of 40= 12.6582 rounded to 12.66
c. What is the likelihood the sample mean is greater
than 320 minutes?
=P (320-330/80/ Sqrt (40))
=P >-10/12.66
=P>-0.79
=P<0.79
=0.5 + P (0<x<0.79)
=0.5 + 0.2852
=0.7852
d. What is the likelihood the sample mean is between
320 and 350 minutes?
=P (320-330/80/ sqrt (40) <x<350-330/80/sqrt (40))
=P (-10/12.66) <x< 20/ 12.66)
=P (-0.79 < x < 1.58)
=P (-0.79 < x < 0) + P(0<x<1.58)
