20 points) Question 4 : Given the frequency table data in the table

below, compute the variance and standard deviation of the data us- ing the grouped data formula. Is the given population normally

distributed?? Use = 0.05. Frequency table

Class Boundaries

fi

xmi

fi xmi

x2mi

5.5-10.5 10.5-15.5 15.5-20.5 20.5-25.5 25.5-30.5 30.5-35.5 35.5-40.5

3

3 11 5 4 2 1

Class

1 2 3 4 5 6 7

Sums

Solution :

fi x2mi

nnn

fi = fixmi = fix2mi

i=1

i=1 i=1

=