A sample offifth-grade classes was studied in an article. One of the variables collected was the class size in terms ofstudent-to-faculty ratio. Thestudent-to-faculty ratios of the 84 fifth-grade classes sampled have a mean of 13.23 and a standard deviation of 2.21. Complete parts(a) through(d) below.

a. Construct the graph shown below.

x

x3s

x2s

xs

x

x+s

x+2s

x+3s

A horizontal x-axis has 7 equally spaced tick marks with the following labels, from left to right: x bar - 3 s, x bar - 2 s, x bar - s, x bar, x bar + s, x bar + 2 s, x bar + 3 s.

x3s

=

6.6

6.6

x+s

=

15.44

15.44

x2s

=

8.81

8.81

x+2s

=

17.65

17.65

xs

=

11.02

11.02

x+3s

=

19.86

19.86

x

=

13.23

13.23

(Type integers or decimals. Do notround.)

b. Apply Property 1 of the empirical rule to make pertinent statements about the observations in the sample.

At least

out of

nothing

fifth-grade classes sampled havestudent-to-faculty ratios between

nothing

and

nothing

.

(Type integers or decimals. Do notround.)