**Answer:**

508

**Step-by-step explanation:**

Take a = 12 and b = 8

**Answer:**

The 80% confidence interval for the the population mean nitrate concentration is (0.144, 0.186).

Critical value t=1.318

**Step-by-step explanation:**

We have to calculate a 80% confidence interval for the mean.

The population standard deviation is not known, so we have to estimate it from the sample standard deviation and use a t-students distribution to calculate the critical value.

The sample mean is M=0.165.

The sample size is N=25.

When σ is not known, s divided by the square root of N is used as an estimate of σM:

The degrees of freedom for this sample size are:

The t-value for a 80% confidence interval and 24 degrees of freedom is t=1.318.

The margin of error (MOE) can be calculated as:

Then, the lower and upper bounds of the confidence interval are:

The 80% confidence interval for the population mean nitrate concentration is (0.144, 0.186).

The answer would be 360 minus 258 because 71 plus 74 and 113 is 258 and you have to minus that by 360

Bascially for answer 360-258

**Step-by-step explanation:**

please type the question properly