Part 2 The attendence records (abscences) of 20 students in a class were recorded due to sickness. Here are the results: 0, 3, 2, 2, 6, 0, 1, 0, 0, 0, 2, 0, 1, 1, 0, 4, 0, 0, 4 c) Find the mean number of days lost d) Find the variance of days lost Assume each observation occurs with a probability of 1/20 - p(X) = 1/N Use the example I used in class (page 25 of class notes) as a template for how to create the table below. e) Create a table to calculate the mean and variance using the following formulaes: $M = E[X] = \sum x \cdot prob(x)$ $\sigma^2 = E[x^2] - M^2$
Added by Steven K.
Close
Step 1
To do this, we need to find the sum of all the observations multiplied by their respective probabilities. The given observations are: 1 The probability of each observation is 1/20. So, the calculation for the mean number of days lost (E(X)) is: E(X) = (1 * Show more…
Show all steps
Your feedback will help us improve your experience
Robin Corrigan and 84 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
Shaiju T.
QUESTION TWO: a) It is known from past experience that 80% of the students in a school do their homework. Find the probability that during a random check of ten students: i. all have done their homework ii. at most two have not done their homework iii. at least one has not done the homework iv. Find the expected number of students who do their homework. v. Find the standard deviation of students who do their homework. b) A population consists of the numbers 1, 3, 5, 7, and 9. i. List all possible samples of size two that can be drawn from the population without replacement. ii. Show that the mean of the sampling distribution of the sample means is equal to the population mean. iii. Calculate the variance of the sampling distribution of the sample mean and show that it is less than the population variance. c) Suppose that X is a discrete random variable with a probability mass function: P(x) = cx^2, x = 1, 2, 3, 4. i. Find the value of c. ii. Find E(X). iii. Find E[X(X-1)].
Chai S.
4.) For the normal random variable X with mean μ = 200 and standard deviation σ = 30, a.) Find the probability P(180 < X < 220) = ? (In the answers below, if the quantity is below the mean enter a negative value.) b.) How many standard deviations above the mean is 220? answer: ? c.) How many standard deviations above the mean is 180? answer: ? d.) What is the variance? σ² = ? e.) Find the value x such that P(X < x) = 97.5%. x = ?
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