Question

Two types of flares are tested for their burning times (in min) and sample results are given below.

Part I : Test the claim that Brand X has a mean less than Brand Y. Use 0.05 significance level.

Brand X	Brand Y
n1 = 35	n2 = 40
x1 = 19.4	x2 = 15.1
Population SD = 1.4	Population SD = 0.8

Claim:

Null Hypothesis:

Alternative Hypothesis:

Calculator Screen Name in Ti 183:

test statistics:

Pvalue/alpha conversion

decision:

Conclusion:

Part II: Construct a 95% confidence interval for U1-U2. Interpret the interval.

Confidence interval name on TI 83

Interval

Interpret.

Answer 1

Claim: Brand X has a mean less than Brand Y

Null Hypothesis:

Alternative Hypothesis:

Calculator Screen Name in Ti 183:

press stat then tests then 2 sampZTest

enter the given data values

n1 = 35	n2 = 40
x1 = 19.4	x2 = 15.1
Population SD = 1.4	Population SD = 0.8

then press enter, we get

test statistics: 16.025

Pvalue/alpha conversion: 0.0000

decision: Reject Ho because the p value is less than significance level of 0.05, this shows that the result is significant.

Conclusion: Result is significant as the p value is less than 0.05 significance level. So, we can conclude that there is sufficient evidence to say that the mean for brand X is less than mean for brand Y

Part II: Construct a 95% confidence interval for U1-U2. Interpret the interval.

Confidence interval name on TI 83

Using Ti 84 calculator

press stat then tests then 2-sampZInt

enter the given data values

n1 = 35	n2 = 40
x1 = 19.4	x2 = 15.1
Population SD = 1.4	Population SD = 0.8

C-level = 0.95

then press enter, we get

Interval: (3.774, 4.826)

Interpret. We are 95% confident that the mean difference between the two means is between the range of 3.774 and 4.826