Question Completion Status: QUESTION 20 A survey among freshmen revealed that the number of hours spent studying the week before final exams was normally distributed with mean 22 and standard deviation 6. What proportion of students studied more than 35 hours? Round your answer to four decimal places. QUESTION 21 The time spent on social media platforms per day by adults has a distribution with a mean of 120 minutes and a standard deviation of 36 minutes. If 64 adults are randomly selected, what is the probability that the sample mean time spent on social media platforms is between 110 and 125 minutes? Round your answer to four decimal places. QUESTION 22
Added by Shannon K.
Close
Step 1
To find the z-score, we use the formula: z = (x - μ) / σ Where: x = the value we want to find the z-score for (35 hours) μ = the mean (22 hours) σ = the standard deviation (6 hours) Plugging in the values, we get: z = (35 - 22) / 6 z = 13 / 6 z ≈ 2.1667 Show more…
Show all steps
Your feedback will help us improve your experience
Ivan Kochetkov and 91 other Intro Stats / AP Statistics educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
A social media research group conducting a study. They wanted to study the sampling distribution of the mean number of hours spent per day on social media for college students. They took a sample of 81 students from a larger university and found that the average number of hours was 4.3 hours, and the standard deviation was 1.8 hours per student. Answer the following questions about the sampling distribution of mean. 1) What is the shape of this sampling distribution of mean of number hours spent on social media? 2) What is the mean of the sampling distribution of mean? That is the mean of all means of all samples of size 81. 3) What is the standard deviation of the sampling distribution? 4) Let's suppose one sample of 81 students gave the mean of 5.0 hours per day on social media. Was this an unusual sample - yes or no? 5) If the sample size were 36, what would the standard deviation of the sampling distribution be?
David N.
A survey of 400 college students found that the mean number of hours students spend on social media each day is 2.3 hours with a standard deviation of 0.5 hours. Construct a 90% confidence interval for the mean number of hours students spend on social media. (Round final answers to three decimal places) What is the margin of error you found in part (a)? (Round final answer to three decimal places) How many students would need to be surveyed in order to have a margin of error of 0.02?
Qudsiya A.
A survey among freshmen at a certain university revealed that the number of hours spent studying the week before final exams was normally distributed with mean 25 and standard deviation 15. A sample of 36 students was selected. What is the probability that the average time spent studying for the sample was between 27.6 and 30 hours studying? Write only a number as your answer. Round to 4 decimal places (for example 0.0048). Do not write as a percentage.
Adi S.
Recommended Textbooks
Elementary Statistics a Step by Step Approach
The Practice of Statistics for AP
Introductory Statistics
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD