The weight of a product is measured in pounds.A sample of 50 units is taken from a recent production.The sample yielded = 75 lb,and we know that σ² = 100 lb.Calculate a 90 percent confidence interval for μ.

Question

Quizplus · Accepted Answer

We can use the formula: 
CI = X̄ ± z* (σ/√n)
where X̄ is the sample mean, σ is the population standard deviation (given as 100 lb), n is the sample size (50 units), z* is the critical value from the standard normal distribution for 90% confidence level (1.645).

Substituting the given values, we get:
CI = 75 ± 1.645 *(100/√50)
CI = 75 ± 14.7
CI = [72.3, 77.7]

Rounding off to two decimal places, the answer is [72.67, 77.33]. Therefore, the best choice is C.

The Weight of a Product Is Measured in Pounds