Assume the average amount of caffeine consumed daily by adults is normally distributed with a mean of 240 mg and a standard deviation of 47 mg. In a random sample of 600 adults, how many consume at least 320mg of caffeine daily? ​

Respuesta :

The confidence interval is between (48.2%, 57.7%)

Using the proportion formula expressed as:

[tex]CI=p\pm z\cdot \sqrt{\frac{p(1-p)}{n} }[/tex]

Get the proportion:

p = 320/600 = 0.53

[tex]z=\frac{x- \mu}{\sigma}[/tex]

[tex]z = \frac{320-240}{47}\\z=\frac{80}{47}\\z= 1.70[/tex]

Substitute into the formula to get the confidence interval to have:

[tex]CI=0.53\pm 1.7\cdot \sqrt{\frac{0.47}{600}}\\CI = 0.53\pm 0.04757\\CI = (0.53-0.04757, 0.53+0.04757)\\CI = (0.482, 0.577)[/tex]

Hence the confidence interval is between (48.2%, 57.7%)

Learn more on  confidence interval here: https://brainly.com/question/20066592