A randomly selected sample of n =51 men in Brazil had an average lifespan of 59 years. The standard deviation was 10 years. Calculate a 98% confidence interval for the average lifespan for all men in Brazil.

Respuesta :

Answer:

[tex]59-2.40\frac{10}{\sqrt{51}}=55.639[/tex]    

[tex]59+ 2.40\frac{10}{\sqrt{51}}=62.361[/tex]    

The 98% confidence interval would be given by (55.639;62.361)    

Step-by-step explanation:

Information given

[tex]\bar X= 59[/tex] represent the sample mean

[tex] s= 10[/tex] represent the sample deviation

[tex] n= 51[/tex] represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

[tex]\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}[/tex]   (1)

The degrees of freedom are given by:

[tex]df=n-1=51-1=50[/tex]

The Confidence is 0.98 or 98%, the significance would be [tex]\alpha=0.02[/tex] and [tex]\alpha/2 =0.01[/tex],and the critical value would be [tex]t_{\alpha/2}=2.40[/tex]

And replacing we got:

[tex]59-2.40\frac{10}{\sqrt{51}}=55.639[/tex]    

[tex]59+ 2.40\frac{10}{\sqrt{51}}=62.361[/tex]    

The 98% confidence interval would be given by (55.639;62.361)