Math  /  Data & Statistics

QuestionSuppose that the amount of time that students spend studying in the library in one sitting is normally distributed with mean 44 minutes and standard deviation 20 minutes. A researcher observed 6 students who entered the library to study. Round all answers to 4 decimal places where possible. a. What is the distribution of XX ? XN(X \sim N( \square \square ) b. What is the distribution of xˉ\bar{x} ? xˉN(\bar{x} \sim N( \square \square ) c. What is the distribution of \square xx ? \square x N(x \sim \mathrm{~N}( \square , \square ) d. If one randomly selected student is timed, find the probability that this student's time will be between 33 and 44 minutes. \square e. For the 6 students, find the probability that their average time studying is between 33 and 44 minutes. \square f. Find the probability that the randomly selected 6 students will have a total study time less than 312 minutes. \square g. For part e) and f), is the assumption of normal necessary? Yes No h. The top 15%15 \% of the total study time for groups of 6 students will be given a sticker that says "Great dedication". What is the least total time that a group can study and still receive a sticker? \square minutes

Studdy Solution
To find the least total time for the top 15% of study times, find the 85th percentile of x\sum x:
Z0.851.036 Z_{0.85} \approx 1.036
Calculate the corresponding total time:
264+1.036(620)264+50.57=314.57 264 + 1.036 \cdot (\sqrt{6} \cdot 20) \approx 264 + 50.57 = 314.57
The least total time is approximately:
314.57minutes 314.57 \, \text{minutes}

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