Author: Anonymous

Two types of flares are tested and their burning times (in minutes) are recorded.  The summary statistics are given below: Brand X Brand Y n=35 n=40 sample mean=19.4 min sample mean=15.1 s=1.4 min s=.8 min Use a .05 significance level to test the claim that the two samples are from populations with the same mean.  Assume that the two samples are independent simple random samples selected from normally distributed populations.  Do not assume the population standard deviations are equal.   The alternative hypothesis is U1 [alt] U2 (type , or =/) The test statistic is:  t=[test] (round to 3 decimal places) The p-value is:  [pvalue] The conclusion about the original claim is:  [claim] s = support the claim r = reject the claim f = fail to reject the claim n = not enough evidence to support the claim

Thirty pairs of data yield r = 0.474 and the regression equation . Also,  the mean of is 18.3.  What is the best predicted value of y for ? 

Use the given data to find the equation of the regression line. Round the final values to three decimal places, if necessary. x 2 4 5 6 y 7 11 13 20 The equation is y = [a] + [b]x

In studying the occurrence of genetic characteristics, the following sample data were obtained. The authors of the study expected each characteristic to occur with the same frequency.  At the 0.05 significance level, test the claim that the characteristics occur with the same frequency.  Characteristic A B C D E F Frequency 28 30 45 48 38 39  What is the test statistic?  [test] (round to 3 decimal places) What is the p-value? [pvalue] (round to 4 decimal places) What is your conclusion regarding the claim that the characteristics occur with equal frequency? [concl] Type r for reject Type s for support Type f for fail to reject Type n for not enough evidence to support

A researcher wishes to test the effectiveness of a flu vaccination. 150 people are vaccinated, 180 people are vaccinated with a placebo, and 100 people are not vaccinated. The number in each group who later caught the flu was recorded. The results are shown below. Vaccinated Placebo Control Caught the flu 8 19 21 Did not catch the flu 142 161 70 Use a 0.05 significance level to test the claim that getting the flu is independent of vaccination treatment. What is the p-value?   Round to 4 decimal places [pvalue] Does the data support that getting the flu is dependent or independent of treatment? [conclusion]  Type dependent or independent.  

Calculate the z-score for each test.  Round your answers to 2 decimal places. Test A:  A score of 82 on a test with a mean of 70 and a standard deviation of 8. [one] Test B:  A score of 82 on a test with a mean of 75 and a standard deviation of 4. [two] Based on the z scores, which test score is better?  [better]

Use the given values of n and p to find the maximum usual value μ + 2σ for a binomial distribution. Round your answer to one decimal place. n = 246, p = 0.15

Determine the minimum sample size required to construct the following confidence interval: Margin of error: 0.012; confidence level: 93%;  p-hat and q-hat are unknown.  In your calculation round the critical value to 3 decimal places.

The table below shows the soft drinks preferences of people in three age groups. cola root beer lemon-lime Under 21 years 40 25 20 between 21 and 40 35 20 30 over 40 years 20 30 35 If one of the 255 subjects is randomly selected, find the probability that the person is over 40 years of age.  Round your answer to 3 decimal places.  

Find the mean of the probability distribution.  Round your anwer to 2 decimal places. x P(x) 0 0.26 1 0.11 2 0.16 3 0.05 4 0.42