The mean is 6,215 and a standard deviation is 7301 words.
Find the numbers of words in limits of one standard deviation:
[tex]-1\le \dfrac{X-16,215}{7,301}\le 1.[/tex]
Solve this inequality:
[tex]-7,301\le X-16,215\le 7,301,\\ \\16,215-7,301\le X\le 16,215+7,301,\\ \\8,914\le X\le 23,516.[/tex]
Conclusion: the numbers of words spoken in a day by women that are usual is [tex]8,914\le X\le 23,516[/tex] and the numbers of words spoken in a day by women that are unusual is [tex]X<8,914 \text{ or } X>23,516.[/tex]
