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SOL A.9 Z SCORES MINI QUIZ



Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 

A speed reading course claims that it can boost reading speeds to 1050 words per minute.
In a random sample of 49 people who took the course, the average was 1020 words per minute, with a standard deviation of 90 words per minute. What is the z-value rounded to the nearest hundredth?
a.
The z-value is –2.33.
b.
The z-value is –16.33.
c.
The z-value is –1.96.
d.
The z-value is 1.96.
 

 2. 

An automobile insurance company claims that its rates for teenage drivers average $410 less per year than the same coverage from another company.
In a random sample of 35 customers, the average savings was $390 per year, with a standard deviation of $55 per year. What is the z-value rounded to the nearest hundredth? 
a.
The z-value is 1.87
b.
The z-value is -1.87
c.
The z-value is –2.15.
d.
The z-value is 2.15
 

 3. 

Suppose that a certain website claims that it averages 4.7 hours of downtime per month. (Downtime is time that the site is not available.)
In a random sample of 17 months, the average downtime was 4.9 hours per month, with a standard deviation of 0.5 hours per month. What is the z-value rounded to the nearest hundredth? 
a.
The z-value is 1.65.
b.
The z-value is -2.21
c.
The z-value is -1.65.
d.
The z-value is 2.21
 



 
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