Question

A student measured the lead content of a paint sample 4 times. The standard deviation of the measurements was found to be 0.76% of the average. Calculate the confidence interval at the 90% confidence level.

Answer 1

Answer:

$CI =0.894%$

Step-by-step explanation:

From the question we are told that:

Sample size $n=4$

Standard deviation $\sigma=0.76\% of \=x$

Confidence level $\mu =90\%=0.90$

Degree of Freedom $Df=n-1=3$

Therefore

Test T from table is given

 $t=2.353$

Generally the equation for Confidence interval CI is mathematically given by

 $CI =t*\frac{\sigma}{\sqrt{n}}$

 $CI =2.353*\frac{0.76}{\sqrt{4}}$

 $CI =0.894%$