Answer:
The margin of error is of 0.3012, and it means that we should be 99% confident that the population mean would be within 0.3012 of the sample mean.
Step-by-step explanation:
Margin of error
[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]
In which [tex]\sigma[/tex] is the standard deviation and n is the size of the sample.
Standard deviation of 1.3
This means that [tex]\sigma = 1.3[/tex]
She surveys 124 families
This means that [tex]n = 124[/tex]
Margin of error and meaning:
[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]
[tex]M = 2.58\frac{1.3}{\sqrt{124}}[/tex]
[tex]M = 0.3012[/tex]
The margin of error is of 0.3012, and it means that we should be 99% confident that the population mean would be within 0.3012 of the sample mean.