Assume that the helium porosity (in percentage) of coal samples taken from any particular seam is normally distributed with true standard deviation 0.74. (a) Compute a 95% CI for the true average porosity of a certain seam if the average porosity for 19 specimens from the seam was 4.85. (Round your answers to

The answer is "(4.518, 5.182)"

Step-by-step explanation:

The aveage porosity for a sample of specimens is

Thus, the confidence interval for the true mean is

Therefore, one can state that the true average porosity will lie  between 4.518 and 5.182 with the 95\% confidence.

93.8

step-by-step explanation:

lets say, first number = x

second number = 3x+7

total = 49

(x)+(3x+7)= 49

4x+7 = 49

4x = 42

x = 42/4

x= 10.5

x= 10.5

3x+7 = 3(10.5)+7 = 93.8

hope this