Assume that the helium porosity (in percentage) of coal samples taken from any particular seam is normally distributed with true standard deviation 0.76.(a) compute a 99% ci for the true average porosity of a certain seam if the average porosity for 16 specimens from the seam was 4.85. (give answers accurate to 2 decimal places.)

Step-by-step explanation:

Formula to calculate the confidence interval for population mean is given by :-

, where = sample mean

n= sample size.

z*= Critical value

= Population standard deviation.

As per given , we have

n= 16

From z-table , the critical value for 99% confidence = z*=2.576

Now , 99% confidence interval for true average porosity of a certain seam will be :

Hence, the required  99% CI for the true average porosity of a certain seam =

87%

step-by-step explanation:

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