In: Statistics and Probability
Question 12
A simple random sample of 12 e-readers of a certain type had the following minutes of battery life.
287, 311, 262, 392, 313, 263, 293, 316, 286, 301, 287, 291
Assume that it is reasonable to believe that the population is approximately normal and the population standard deviation is 62. What is the upper bound of the 95% confidence interval for the battery life for all e-readers of this type?
Round your answer to one decimal places (for example: 319.4). Write only a number as your answer. Do not write any units.
Question 15
A random sample of 13 students were asked how long it took them to complete a certain exam. The mean length of time was 109.5 minutes, with a standard deviation of 68.2 minutes. Find the lower bound of the 90% confidence interval for the true mean length of time it would take for all students to complete the exam.
Round to one decimal place (for example: 108.1). Write only a number as your answer. Do not write any units.
Question 12
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Since population standard deviation is unknown and sample size (n) is less than 30, Use students t-distribution.