Statistics Fundamentals GMLE Practice Questions (Page 2)

Questions 6–10

1. 6expert · medium

   A data scientist constructs a 95% confidence interval for the mean response time of a web service: [120 ms, 180 ms]. They want to reduce the width of the interval without losing confidence. Which approach is most effective?

   • ADecrease the confidence level to 90%
   • BUse a different sample that has a larger standard deviation
   • CIncrease the sample size
   • DIncrease the confidence level to 99%
   Reveal Solution Discussion Select an answer first
2. 7application · medium

   A quality control engineer measures the diameter of ball bearings produced by a machine. The diameters are normally distributed with a mean of 10 mm and a standard deviation of 0.2 mm. What percentage of ball bearings will have a diameter between 9.8 mm and 10.2 mm?

   • AApproximately 95%
   • BApproximately 68%
   • CApproximately 50%
   • DApproximately 99.7%
   Reveal Solution Discussion Select an answer first
4. 8foundation · easy

   In stratified sampling, the population is divided into subgroups, and then samples are drawn from each subgroup. What is the primary benefit of this approach?

   • AIt eliminates the need for random selection.
   • BIt guarantees that the sample is representative of the entire population without any bias.
   • CIt ensures that each subgroup of interest is represented in the sample.
   • DIt is always cheaper than other sampling methods.
   Reveal Solution Discussion Select an answer first
5. 9application · medium

   A/B testing team at a retail site runs an experiment to increase checkout completion. They collect 10,000 users per variant and observe a 0.8% lift in conversion for the new checkout flow, with a p-value of 0.04. The product manager wants to launch immediately. The data scientist notes that the team ran 20 similar tests last month. What is the most important additional consideration before declaring the result significant?

   • AAdjust the significance threshold for multiple comparisons, e.g., using a Bonferroni correction.
   • BConfirm that the two variants were assigned randomly.
   • CVerify that the sample size was large enough to detect a 0.8% effect.
   • DCheck whether the effect size is practically meaningful for the business.
   Reveal Solution Discussion Select an answer first
6. 10foundation · easy

   After conducting a hypothesis test, a data scientist obtains a p-value of 0.03. Using a significance level of 0.05, what is the correct conclusion?

   • AReject the null hypothesis because the p-value is less than 0.05.
   • BFail to reject the null hypothesis because the p-value is less than 0.05.
   • CReject the alternative hypothesis because the p-value is less than 0.05.
   • DAccept the null hypothesis because the p-value is greater than 0.05.
   Reveal Solution Discussion Select an answer first