TI-84
Random sample of 30 sandwiches has a mean of 1042.7 mg of sodium a population std dev of 344.9 mg. Construct an 80% CI.
z-Interval
Random sample of 189 lobsters had a mean weight of 17 oz and sigma of 3.9 oz. Construct a 98% CI for the population mean.
(16.3, 17.7)
What is a type I error?
reject the null when it was correct
When determining sample size what do we use for p if we have no estimate?
0.5
Which of the following is not a country?
Tasmania
Togo
Tonga
Tunisia
Tuvalu
Tasmania
Random sample of 8 people, the mean commute time to work was 35.5 min and the std dev was 7.2 min. Construct a 95% confidence interval.
t-Interval
The following confidence interval is obtained for a population proportion (0.336, 0.376). Find the point estimate,
0.356
Natl Weather Service says the mean daily high for October was 56°. A local weather service wants to the test the claim because they think it is lower. A sample of mean temps over the past 31 years yielded a mean of 54°. The population standard deviation is known to be 5.6°. Test the claim at the 0.01 level.
z = -1.99
p = 0.02
Fail to Reject
A university proposes to do an analysis of the proportion of grads who have not found employment in their major field. In previous years the percent averaged 0.09. You wants the margin of error to be within 0.03 at a 99% confidence level. Find the minimum sample size.
604
Which of the following is not a country?
Bahrain
Bhutan
Borneo
Brunei
Burundi
Borneo
County considering raising the speed limit because they claim the. mean speed is greater than 45 mph. SRS of 25 vehicles has a mean of 48 mpg and s = 5.4. At alpha = 0.10, do you have evidence to test the claim?
t-Test
Find the critical value z that corresponds to a 91% confidence interval.
1.70
In an SRS of 500 people aged 20-24, 22% were smokers. In an SRS of 450 people aged 25-29, 14% were smokers. Test the claim that the proportion of smokers in the two age groups is the same at the 0.01 level.
z = 3.19
p = 0.001
Reject
Scores on a certain test are normally distributed with a variance of 15. You want to estimate the mean score achieved by all adults on this test. Find the sample size needed to assure with 98% confidence that the sample mean will not differ from the population mean by more than 4 units.
6
Which of the following is not a country?
Equatorial Guinea
Guinea
Guinea-Bissau
Papua New Guinea
Western Guinea
Western Guinea
Mean ACT for 20 male high school students is 21.1 with s = 5. The mean ACT for 19 female students was 20.9 with s = 4.7. At alpha = 0.01, can you reject the claim that males and females have equal ACT scores?
2-SampleTInt
109 Brand X oil filters and 99 Brand Y were tested for mg of residue with the following results. Determine a 95% confidence interval for the difference in residue.
Mean for Brand X = 4.1 and s = 0.13
Mean for Brand Y = 4.4 and s = 0.76
(-0.45, -0.15)
Reject if t > 1.645
You want to estimate the mean time college students spend watching videos each day. The estimate must be within 1 minute of the population mean. Determine the required sample size to construct a 99% confidence interval. Assume sigma = 2.4 minutes.
39
Which of the following is not a country?
Gabonia
The Gambia
Georgia
Ghana
Guyana
Gabonia
A drug company guarantees its new drug reduces blood pressure. You collect data on 9 patients before and 2 hours after taking the drug and want to test the company's claim at the 5% level.
t-Test
10 families are tested for gallons of water used before and after watching a conservation video. Construct a 90% confidence interval for the mean of the differences.
Before: 33 33 38 33 35 35 40 40 40 31
After: 34 28 25 28 35 33 31 28 35 33
(-7.8, -1.8)
10 families are tested for gallons of water used before and after watching a conservation video. Test at the 0.05 level the claim that the mean is the same before and after the viewing.
Before: 33 33 38 33 35 35 40 40 40 31
After: 34 28 25 28 35 33 31 28 35 33
t = -2.894
p = 0.0178
Reject the null
Find the minimum sample size needed to estimate a population proportion at the 99% confidence level in order to ensure that the estimate is accurate within 4% of the population proportion.
1037
Which of the following is not a country?
Mauritania
Mauritius
Micronesia
Moldova
Moravia
Moravia