BSEC Test 2 Pg 1

# BSEC Test 2 Pg 1 - Confidence level(confidence coefficient...

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Confidence level (confidence coefficient) 1-a Takes 3 values, 0.01, 0.05, 0.1 Za/2 case A, o=0.10 Zo/z=1.645 case B, o=0.05 Zo/z=1.96 case C, o=0.01 Zo/z=2.575 Known that: 1. The population ={repair costs of all broken washing machines} The population mean U (i.e., the average repair cost of all broken machines) us unknown. 2. Sample size, n=40 Sample={x, x1, x2, x3, …} 3. Sample mean X_=\$120 4. sample standard deviation, s=\$17.50 (X1-x_)^2+(X2-x_)^2….(X40- x_)^2/40-1 5. Confidence level is 1-o=0.95 (95%), o=0.05 The 95% confidence interval for the unknown population mean U (the unknown average repair cost of all broken washing machines) is given by: 120+-(Z0.05/2)*17.5/sqrt40 120+-(1.96)17.5/6.225 120+-5.42 114.58, 125.42 we’re 95% confident that the unknown population U (the unknown average repair cost of all broken machines) lies between 114.58 & 125.42 Known that: 6. The population ={calorie reading of all 8 oz servings} The population mean U (i.e., the average calorie reading of all 8 oz

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Unformatted text preview: servings) us unknown. 7. Sample size, n=31 Sample={x, x1, x2, x3, …} 8. Sample mean X_=99.3 9. sample standard deviation, s=41 (X1-x_)^2+(X2-x_)^2….(X40-x_)^2/40-1 10. Confidence level is 1-o=0.90 and 0.95 The 90% confidence interval for the unknown population mean U (the unknown average calorie reading of all 8 oz servings) is given by: 99.3+-(Z0.1/2)*41.5/sqrt31 99.3+-(1.645)41.5/5.567 99.3+-12.263 87.037, 111.563 we’re 90% confident that the unkown populaton U (the unknown average calorie reading of all 8 oz servings) lies betweem 87.037 & 111.563 1. X_+-Za/z*S/sqrtN for n>30 2. X_+-(t a/zn-1)S/sqrtN for N<30 1) 1-o=95%; thus, o=0.05 2) the maximum error of estimation is E=1 3) population standard deviation, O=4.8 N= (Zo/2*O / E)^2 (Z0.05/2*O / 1)^2 (1.96*4.8/1) ^2 =88.51 = 89 ^p+-Zo/2 sqrt(^p(1-^p) / n) N=(Za/2)^2 ^p(1-^p) / E^2 1, 1-o=0.95; o=0.05 2. E=0.03 Part A. (Za/2)^2 ^p(1-^p) / E^2...
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