1.) Find the z-score in the standard normal distribution such that 35% of the ar
ID: 3135091 • Letter: 1
Question
1.) Find the z-score in the standard normal distribution such that 35% of the area under the curve will be to the right of this z-score. (round answer to the nearest hundredth decimal place)
2.) The DMV reports that the average age of a vehicle in our county is 9 years old (108 months). Assume that the distribution of a vehicle ages is normally distributed with a standard deviation of 18 months. What percent of vehicles in the county are more than 12 years old (144 months). Give your answer as a decimal rounded to four decimal places.
3.) The average number of hours that a student spends per day working at a computer is 4.3 hours. This distribution is normally distributed with a standard deviation of 0.8 hours. What percentage of students spend more than 5.5 hours per day working at a computer? Give your answer as a decimal rounded to four decimal places.
4.) AAA reports that the average time it takes to respond to a roadside emergency is 25 minutes. The times are normally distributed with a standard deviation of 4.5 minutes. What is the probability that you will wait for AAA for less than 30 minutes for a randomly selected roadside emergency? Give your answer as a rounded four place decimal.
5.) Women's heights are normally distributed with a mean of 64.5 inches and a standard deviation of 2.3 inches. If a woman is selected at random, what will be the probability that her height will be greater than 66.5 inches? (Give your answer as a decimal rounded to four places)
6.)The amount of money that a student at Harvard University carries on his/her person is normally distributed with a mean of $25 and a standard deviation of $5. What is the probability that a randomly selected Harvard student will have more than $10 on his/her person? (give your answer as a decimal rounded to 4 decimal places)
7.) The average beginning annual salary for teachers in california is $41,181. Assume that this is a normal distribution with a standard deviation of $725. One quarter of starting teachers in CA will make how "at least" much money per year? (round to the nearest dollar)
8.)To qualify for the Police Academy, candidates must score in the top 5% on the General abilities test. The mean and standard deviation of the general abilities test are 300 and 15 respectively. What is the lowest score that a candidate can have and still qualify for the police academy? Your answer should be "rounded up" to the nearest whole number.
9.)The IQ scores for individuals are normally distributed with a mean of 100 and a standard deviation of 15. Find the z-score for an individual whose IQ is 120. Round your answer to the nearest hundredth decimal place.
10.) For a particular medical study, a researcher wishes to study the middle 50% of the population based on systolic blood pressure. If the mean systolic blood pressure is 120 and the standard deviaion is 12, what is the upper systolic blood pressure reading that would qualify people to be in the study? (round your answer to the nearest whole number)
Explanation / Answer
1.
Hence, the area to the left is 1 - 0.35 =0.65.
We get the z score from the given left tailed area. As
Left tailed area = 0.65
Then, using table or technology,
z = 0.39 [ANSWER]
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2.
We first get the z score for the critical value. As z = (x - u) / s, then as
x = critical value = 144
u = mean = 108
s = standard deviation = 18
Thus,
z = (x - u) / s = 2
Thus, using a table/technology, the right tailed area of this is
P(z > 2 ) = 0.022750132 [ANSWER]
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