StatsTest4Solutions

StatsTest4Solutions - Sh i I ‘ V w W_WWWW-IMM.t W t...

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Unformatted text preview: Sh i. _ I ‘ V w. W _WWWW-IMM. .t ; . W t. Statistics & Pronabinty - Test #4 (Ci ape: 18 and Confidence LEICSXV’flle ow All World 31 A state’s Department of Education reports that 12% of the high school students in that stste attend private high schools. The State University wonders if the percentage is the same in their applicant pool. Admissions officers plan to check a random sample of the over 10,000 applications on file to estimate the percentage of students applying for admission who attend private schools. a. They actually select a random sample of 450 applications, and find that 46 of those students attend rivate schools. Create thevconfidence interval. I8; 04; 5‘: ;' Jim“ 70492 e 5.02%; x. .o a o. b. interpret the confidence interval this context $56,805 confl‘l J x v so this 99:17:72». (:1. v his S+‘Ud—ét"."$ appi ~43 not also“. cg flrzva . -. 7+. 4‘ 7r a: r“) (7} e C. if We increased the confidence level. would the Margin of Error increase or decrease Please explain your answer. It? in? it:£%<’0.£§'d fin?) Noon: :mt‘rf‘ 3:949 Q Mira/Qt" nei'nli}eri/ ) .t‘ wi gr S’S'f‘ Q. Should the admissions officers conclude that the p reentage of private school students in their applicant pool is lower ti an the statewide enrollment rate of 12%? Explain Call”- (Duct-4&2, {fiat-7 lit-£1 .30 +14% -’” g; «+6’MITQLQ, M is": 376 i’WW‘ eiieved that nearsighted-Hess affects abou: 12% of children. A school district gives 3 incoming kindergarten ckildren a EX: lain Why a Normal model can be used to describe the sampling a" ii," ., '3. Find the mean an C. Sketch and clear/1&1abei-ri‘he—modeiwiisfligg the 68-95—99] Ruie - p over 15% of {he ch iidren wiii be found to be . 4"“! and"? , y“ ' r -—v -— é fV—mm ‘ av '~ K; ' FEM incurs-Q ,1 [OT » k: QJ‘T'” a, , r , . {.\“,’:... _ r; u? f 5" C so 1" * U ’ C :5.‘;‘. 45, , a .x N V: [fluid 7 a ,, n; . “L 4.23/13 3. Wildlife scientists stud 1:10 21 certain s ecies of freos know that as: records indicate the adi‘lts 4 D _ 0 Should wewh c, an average of ME grams with a standard deviation of 14 grams. The researchers collect a random sample of 50 adult frogs and we igh them. in their sample the mean weight was only 110 grams. a. Explam why a l Tormal model can be used to describe the sampling distribution for the sample mean. 7. g, .. , 7 7 . 117' 3‘5.) "\ x SALHT 6“ >3" b. Find the mean and the standard deviation of {he trigdel r i; k<é ' R x: flq / 301 / ,4 7 x \7 ‘ f' l I — a): m " ‘ W” Cl. One of the sczentxsts IS alarme 7 fearing that enmro ntal ‘C‘idnges may be adversely affecting the frogs. Do you :hink this sample result is unusually low? Explain. A 3" ‘7 4s A professor at a large university believes that students take an average of 15 credit hours per term. A random sample of 24 students in her class of 250 students had a mean of 16.6 credit hours and a standard deviation of 2.22 credit hours. 3. Find a 95% confidence interval for t- professor’s class. c. Does this confidence interval indicate that students are taking more credit hours than the professor believes? Explain your answer. o ...
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This note was uploaded on 04/12/2011 for the course STA 215 taught by Professor Tba during the Spring '08 term at Grand Valley State.

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StatsTest4Solutions - Sh i I ‘ V w W_WWWW-IMM.t W t...

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