ety researcher is studying the design of a freeway sign and is interested in the mean maximum distance at which drivers are able to read the sign. The maximum distances (in feet) at which a random sample of 16 drivers can read the sign are as follows: 460 550 660 600 600 660 300 500 420 660 250 460 550 600 500 550 The mean of the sample of 16 distances is 520 feet with a standard deviation of 121 feet. (a) What assumption must you make before constructing a confidence interval?
A highway safety researcher is studying the design of a freeway sign and is interested in the mean maximum distance at which drivers are able to read the sign. The maximum distances (in feet) at which a random sample of 16 drivers can read the sign are as follows:
460 550 660 600 600 660 300 500 420 660 250 460 550 600 500 550
The mean of the sample of 16 distances is 520 feet with a standard deviation of 121 feet.
(a) What assumption must you make before constructing a confidence interval?
1) The population distribution is Uniform.
2) The population distribution is Normal.
(b) At the 90% confidence level what is the margin of error on your estimate of the true mean maximum distance at which drivers can read the sign.
Answer=_________ feet (round to the nearest whole number)
(c) Construct a 90% confidence
Lower value=_______ feet (round to the nearest whole number)
Upper value= _______feet (round to the nearest whole number)
(d) There is a 10% chance the error on the estimate is bigger than what value?
Answer=______ feet (round to the nearest whole number)
(e) The researcher wants to reduce the margin of error to only 13 feet at the 90% confidence level. How many additionaldrivers need to be sampled? Assume the sample standard deviation is a close estimate of the population standard deviation.
Answer=_______
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