1 / 6

Sampling Distributions of Proportions

Sampling Distributions of Proportions. Formulas:. These are found on the formula chart!. Assumptions (Rules of Thumb). Sample size must be less than 10% of the population Sample size must be large enough to insure a normal approximation can be used. np > 10 & n (1 – p) > 10.

sakina
Download Presentation

Sampling Distributions of Proportions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Sampling Distributions of Proportions

  2. Formulas: These are found on the formula chart!

  3. Assumptions (Rules of Thumb) • Sample size must be less than 10% of the population • Sample size must be large enough to insure a normal approximation can be used. np > 10 & n (1 – p) > 10

  4. Based on past experience, a bank believes that 7% of the people who receive loans will not make payments on time. The bank recently approved 200 loans. What are the mean and standard deviation of the proportion of clients in this group who may not make payments on time? Are assumptions met? What is the probability that over 10% of these clients will not make payments on time? Yes – np = 200(.07) = 14 n(1 - p) = 200(.93) = 186 Ncdf(.10, 1E99, .07, .01804) = .0482

  5. Suppose one student tossed a coin 200 times and found only 42% heads. Do you believe that this is likely to happen? np = 200(.42) = 84 & n(1-p) = 200(.58) = 116 Since both > 10, I can use a normal curve! Find m & s using the formulas. No – since there is approximately a 1% chance of this happening, I do not believe the student did this.

  6. Assume that 30% of the students at BGHS wear contacts. In a sample of 100 students, what is the probability that more than 35% of them wear contacts? Check assumptions! mp-hat = .3 & sp-hat = .045826 np = 100(.3) = 30 & n(1-p) =100(.7) = 70 Ncdf(.35, 1E99, .3, .045826) = .1376

More Related