Work sheet #9 STA 2023

For #1 – 9, use the appropriate formula to find the a) Margin of error and b) Confidence interval. Show the formula and your “plug-ins”.

1) Distances driven by male students in one year: 90% confidence, n = 100, and s = 3577

2) 35 skulls obtained for Egyptian males who lived around 1850 BC: 95% confidence, mm and s = 3.48 mm

3) Times between uses of a TV remote control: 99% confidence, n =100,

seconds and s = 2.65 seconds.

4) Math SAT scores for women: 95% confidence, n = 15, , s = 108

5) IQ scores of professional athletes: 98% confidence, n = 12, , s = 12

6) You crash test 10 Dodge Viper sports cars. Mean of the damage costs: 90% confidence, , s = $15873

7) Population proportion 99% confidence, n = 750, x = 150

8) Confidence level 95%, n = 1350, x = 216

9) Confidence level 98% and = .37 and n = 500

For #10 – 18, a) tell which calculator screen to use to find the confidence interval and

b) use it to find the confidence interval .

10) Maximum heart rate during automated snow removal: 95% confidence, n = 10, , s = 18, n = 10

11) Confidence 98%, n = 1068 and x = 237

12) 98% confidence for Nitrous oxide emissions in grams per mile.

sample: 0.06 0.11 0.16 0.15 0.14 0.08 0.15

(Put in a list & on the screen highlight DATA)

13) 95% confidence for drive-through service times at a Burger King where n = 95, seconds and s = 55.5 seconds.

14) Replacement times for a sample of 25 TV sets purchased several years ago: 90% confidence interval, years and s = 1.1 years.

15) Survey of 4276 households, 4019 had telephones, 99% confidence interval.

16) 99% confidence for pizza delivery times: n = 50, minutes, s = 2.8 minutes.

17) A survey of 1233 people who took trips, 111 said their trip included a visit to a theme park. 96% confidence interval.

18) Listed below are the values (in dollars) of items shoplifted and recovered for a store. 99% confidence (Put in a list. Then go to Calc, 1-Var Stats to get s. Then go to ZInterval and put in s where it asks for “sigma”.)

145 144 543 347 150 402 34 120 135

16 101 38 209 38 55 24 18 146

100 450 17 25 40 38 530 10 275

380 163 25 230 17 102 390 80 331