Question

1) A random sample of 130 car owners were asked how many years they had owned their current car. The results were ¯x=4x¯=4 years and s=1.7s=1.7. Estimate how long ago people typically acquired their car (at the 99% confidence level).
Here, we should use:

• 2-SampZInt
• TInterval
• 1-PropZInt
• ZInterval
• 2-SampTInt
• 2-PropZInt

2) Students in two different classes used two different textbooks to learn the same subject matter. We wish to estimate with 90% confidence how much better students in Class B performed.

A	B
74	83
65	85
71	80
68	65
76	66
81	77
70	76

In order to construct a 90% confidence interval here, we should use:

• TInterval
• ZInterval
• 1-PropZInt
• 2-SampTInt
• 2-SampZInt
• 2-PropZInt

3) Medicine A treats Symptom Y. 800 subjects with Symptom Y volunteered to take Medicine A and 470 were treated effectively. In order to estimate with 95% confidence the medicine's efficacy, we should use:

• 2-SampTInt
• TInterval
• 2-SampZInt
• 1-PropZInt
• ZInterval
• 2-PropZInt

Answer 1

1)

There is one sample of 130 car owners and we do not know the population standard deviation, we use T-Interval

2)

There are two samples of students of class A and B and we do not know the population standard deviation, we use

2-SampTInt

3)

There is one sample of 800 subjects and need to estimate the proportion of subjects treated effectively., we use

1-PropZInt