Final answer:
To find the confidence interval for a random sample, use the formula: Confidence interval = Sample mean ± (Critical value) * (Standard deviation / sqrt(sample size)). For this sample, the confidence interval is approximately 2.04 to 2.36.
Step-by-step explanation:
To calculate the confidence interval for a random sample, we can use the formula:
Confidence interval = Sample mean ± (Critical value) * (Standard deviation / sqrt(sample size))
In this case, the sample mean is 2.2, the standard deviation is 0.84, and the sample size is 12. The critical value for a 90% confidence interval is 1.96.
Plugging in these values, we get:
Confidence interval = 2.2 ± (1.96) * (0.84 / sqrt(12))
Calculating this, we find that the confidence interval is approximately 2.04 to 2.36.