HW8_skeleton

9.1

• 1. Point estimate
• 2. Level of confidence, (1-a) * 100 %
• 3. False
• 4. Critival value
• 5. Increases
• 6. Decreases
• 7. 1.645
• 8. 2.575
• 9. 2.33
• 10. 1.75
• 11. Point estimate: 0.225 Margin of error: 0.024 X: 270
• 12. Point estimate: 0.0625 Margin of error: 0,0115 X: 70
• 15. Lower bound: 0.146 Upper bound: 0.253
• 16. Lower bound: 0.319 Upper bound: 0.480

1. We need a confidence interval
2. Too many confidence levels
3. This is the correct one
4. It’s not true because there were only one sample

• 1. 0.18

  2. 340 > 10. Both normality and independence conditions are satisfied

  3. Lower bound: 0.166 Upper bound: 0.193

  4. I am 90 % confident that the proportion of Americans aged 18 and older who have donated blood in the past two years is between 0.166 and 0.193

• 1. 0.4302

  2. 282 >10. Both normality and independence conditions are satisfied

  3. Lower bound: 0.407 Upper bound: 0.452

  4. I am 95 % confident that the proportion of workers and retirees in the United States 25 years of age and older who have less than $10,000 in savings is between 0.407 and 0.452