hw.prop.CI.Hypo.pVal.STS.KEY

55045 0099 n 25 pcv 055 2330099 055 023

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: p < 0.55 2. Determine critical value ^ ^ pcv - p pcv - 0.55 KEY: Zcv = -2.33 = p(1- p) 0.55(0.45) 0.099 = n 25 ^ pcv = 0.55 – 2.33(0.099) = 0.55 – 0.23 = 0.32 3. 4. 5. 8. 8a. 8b. State decision rule KEY: Reject Ho if ^sample < ^cv = 0.32 p p p State decision KEY: Since ^sample = 9/25=0.36 NOT < ^cv = 0.32 can NOT reject Ho p State conclusion KEY: the population proportion p is probably ≥ 0.55 We'll test at α = 0.05 whether the population proportion of airline passengers checking baggage is at most 0.55 . A sample of 25 passengers showed 11 checked their baggage. Determine whether it is OK to use the Normal distribution for this problem. KEY: OK to use Z if np>5 and n(1-p)>5: 25(0.55)=13.75 > 5, 25(0.45)=11.25 > 5 so OK to use Z Hypothesis testing using the STS method: Show all work including the raw formula with symbols (no numbers). No credit unless proper subscripts are used everywhere. Use 3 decimal places for the standard deviation. Draw a graph and fill it out completely. 1. State Hypotheses KEY: Ho p ≤ 0.55 H1: p > 0.55 2. Determine critical value KEY: Zcv = 1.645 3. State decision rule: KEY: reject Ho if Zsample > Zcv = 1.645 4. State decision KEY: Since Zsample = ^ psample - p KEY: Zsample = Zsample = p(1- p) n [11/25=0.44] - 0.55 -0.11 = 0.099 = -1.11 0.55(0.45) 0.099 = 25 Since Zsample = -1.11 NOT > Zcv = 1.645, can NOT reject Ho 5. State conclusion KEY: the population proportion p probably IS ≤ 0.55 8c. Note that the p-value is > 0.5000: area for -1.11 is 0.3665, so p-value = 0.5000 + 0.3665 = 0.8665 . p-value is on the same side as alpha – it has the same "tail" as alpha....
View Full Document

This note was uploaded on 01/27/2013 for the course STAT 385 taught by Professor Szatrowski during the Spring '08 term at Rutgers.

Ask a homework question - tutors are online