An automobile manufacturer claims that its van has a 40.3 miles/gallon (MPG) rating. An independent testing firm has been contracted to test the MPG for this van since it is believed that the van has an incorrect manufacturer's MPG rating. After testing 250 vans, they found a mean MPG of 39.9. Assume the standard deviation is known to be 2.4. A level of significance of 0.05 will be used. Find the value of the test statistic. Round your answer to 2 decimal places.

The value of the test statistic is -2.64.

Step-by-step explanation:

The test statistic is:

In which X is the sample mean, is the expected(claimed) mean, is the standard deviation and n is the size of the sample.

An automobile manufacturer claims that its van has a 40.3 miles/gallon (MPG) rating.

This means that

After testing 250 vans, they found a mean MPG of 39.9. Assume the standard deviation is known to be 2.4.

This means, respectively, that:

So

The value of the test statistic is -2.64.

a) one student is chosen from classroom a, then a student is chosen from classroom b.  

step-by-step explanation:

independent events are ones in which the probability of one event does not affect the probability of the second event.

one student is chosen from classroom a; this does not affect the chances of choosing a student from classroom b.   this makes these independent events.

when one card is chosen from a standard deck and then set aside before a second card is chosen, the probability of the second card being chosen changes.   this makes them dependent events.

when one student is chosen from classroom a and then a second student is chosen from classroom a, the probability of choosing the second student changes.   this makes them dependent events.

when a letter is chosen from the alphabet and then a second letter is chosen, the probability of choosing the second letter changes.   this makes them dependent events.

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