from the Bay area are randomly chosen. We are interested in the average cost of gasoline for the 16 gas stations. What is the approximate probability that the average price for 16 gas stations is over $4.69?
0.1587
Almost zero
Unknown
0.0943
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New SD = .10/SQRT(16) = .025
P(x > 4.69) = 1 - P(x < 4.69) In Excel, =1-NORM.DIST(4.69,4.59,.025,TRUE)
You might get an answer with an "E" in it. The "E"; means scientific notation. 3.16712E-05 decimal answer is, .0000316712
Question 6
1 / 1 point
The average lifetime of a set of tires is three years. The manufacturer will replace any set of tires failing within two years of the date of purchase. The lifetime of these tires is known to follow an exponential distribution. What is the probability that the tires will fail within two years of the date of purchase?
0.8647
0.2212
0.4866
0.9997
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P(x < 2)
In Excel,
=EXPON.DIST(2,1/3,TRUE)
Question 7
1 / 1 point
The commute time for people in a city has an exponential distribution with an average of 0.5 hours. What is the probability that a randomly selected
person in this city will have a commute time between 0.4 and 1 hours? Answer: (round to 3 decimal places)
___.314
___
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P(.4 < x < 1)
P(x < 1) - P(x < .4)
In Excel,
=EXPON.DIST(1,1/0.5,TRUE)-EXPON.DIST(0.4,1/0.5,TRUE)
Question 8
1 / 1 point
The life of an electric component has an exponential distribution with a mean of 8 years. What is the probability that a randomly selected one
such component has a life less than 5 years? Answer: (round to 4 decimal places)
___.4647
___
Hide question 8 feedback
P(x < 5) In Excel, =EXPON.DIST(5,1/8,TRUE)
Question 9
1 / 1 point
The average lifetime of a certain new cell phone is three years. The manufacturer will replace any cell phone failing within two years of the date of purchase. The lifetime of these cell phones is known to follow an exponential distribution. What is the median lifetime of these phones (in years)?
5.5452
1.3863
0.1941
2.0794
Hide question 9 feedback
Median Lifetime is the 50th percentile. Use .50 in the equation and the rate of decay is 1/3
Question 10
1 / 1 point
The waiting time for a table at a busy restaurant has a uniform distribution between 0 and 10 minutes. What is the 95th percentile of this distribution? (Recall: The 95th percentile divides the distribution into 2 parts so that 95% of area is to the left of 95th percentile) _______ minutes Answer: (Round answer to one decimal place.)