Answer:
Step-by-step explanation:
Answer:
Step-by-step explanation:
We want to determine a 80% confidence interval for the mean mercury concentration of water samples
Number of samples. n = 4
Mean or average = 0.470 cc/cubic meter
Standard deviation, s = 0.0581
For a confidence level of 80%, the corresponding z value is 1.28. This is determined from the normal distribution table.
We will apply the formula
Confidence interval
= mean +/- z ×standard deviation/√n
It becomes
0.470 +/- 1.28 × 0.0581/√4
= 0.470 +/- 1.28 × 0.0566/2
= 0.470 +/- 0.036
The lower end of the confidence interval is 0.470 - 0.036 =0.434
The upper end of the confidence interval is 0.470 + 0.036 =0.506
In conclusion, with a 80% confidence interval, the mean lead mean mercury concentration of the water samples is between 0.434 cc/cubic meter and 0.506 cc/cubic meter
