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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).
Let the length of the shortest side = x
The two longer sides that are equal = 3x
The are two equal longer sides, so their total is 3x + 3x = 6x
3x+ 3x + x= 35 Collect like terms on the left
7x = 35 Divide by 7 on both sides
x = 35/7
x = 5
Answer
Two long sides -- 15 cm each
Shortest side -- 5 cm
Answer:
correct
Step-by-step explanation: