Q9: The jeweler asks whether at least 65% of the diamonds in the new shipment will be premium or ideal cut. Based on the confidence interval, which of the following will support your response?
- The confidence interval for the proportion of premium or ideal diamonds includes 0.65, so it is reasonable to expect that at least 65% of the shipment will be premium or ideal cut.
- The sample proportion is greater than 0.65, so you can guarantee that at least 65% of the shipment will be premium or ideal cut.
- Since 0.65 is below the upper bound of the confidence interval, it is unlikely that at least 65% of the shipment will be premium or ideal cut.
- The confidence interval suggests that exactly 90% of the shipment will be premium or ideal cut.
For the above question the correct answer is [staff note: redacted] which does not include 0.65. Do we round-off the interval to 2 digits and then mark the answer?
Any clarification would be very helpful.
Thanks,
Neeraj
confidence level is 50% and not confidence interval.
please click on name and then DM the screenshot of your calculations.
As I am not mentor for this course, I do not have access to the course material or quiz, but in case you need assistance, I am happy to help.
My answer was based on the question you shared only as I do not have access to this course material.
In statistics, a confidence interval is a range of values within which a population parameter (like the mean) is likely to fall, while confidence level is the probability that the interval contains the true population parameters if the process of sampling and calculating intervals were repeated many times.
Hi Neeraj! The question asks “at least” so you will have to check if the confidence interval exceeds that value. In other words, if the lower bound is already greater than the value in question, then you can be confident that the true proportion will likely be higher than the said value. We will improve the answer choices and feedback to avoid confusion. Hope this helps!
I will have to remove some parts of this thread because it gives the answer away for some of the learners. But good catch! Thank you for the feedback!