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).
For example:
L plus W
3 plus 6= 9
I plus W
4 plus 6= 10
total: 9+10= 19
(this is just an example)
Answer:
if each commercial lasts 1/2 minute how many commercials are there in a 4-hour program?
480
Step-by-step explanation:
4 hours= 240 mins
240/0.5=480
Answer:
Step-by-step explanation: 100 divided by 20 is 5 therefore, each question is worth 5%. take how many questions she got right and multiply by 5. then determine if her score is less than or greater then 90%.