Answer:

Step-by-step explanation:
Given

Required
Determine the yearly cost
To do this, we multiply the monthly subscription by 12



<em>Hence, the yearly servics cost is $59.88</em>
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).
Answer:
44 gallons
Step-by-step explanation:
3960/3=1320
Each person used 1320 in one month
1320/30=44
Amount of person used / 30 days = gallons used each day
Answer:
The area of this trapezoid is 28 square meters
Step-by-step explanation:
A=a+b
/2 h