1. What are the characteristics of a good measure of central tendency?
[5 Marks]
(b) What are the uses of averages? [5 Marks]
2. For each one of the following null hypothesis, determine if it is a left-tailed, a right-tailed, or a two-tailed test. [10 Marks}
a. μ ≥ 10
b. P ≤ 0.5
c. μ is at least 100.
d. μ ≤ -20
e. p is exactly 0.22
3. What is test statistic? Why do we have to know the distribution of a test statistic? [10 Marks]
4. Suppose you are sampling from a population with mean μ= 1,065 and standard deviation σ = 500. The sample size is n=100. What are the expected value and the variance of a sample mean ̅ ? [ 10 Marks]
5. The time it takes an international telephone operator to place an overseas phone call is normally distributed with mean 45 seconds and standard deviation 10 seconds. [10 Marks]
a) What is the probability that my call will go through in less than 1 minute?
b) What is the probability that I will get through in less than 40 seconds?
6. The following data are the number of tons shipped weekly across the pacific by a shipping company. [10 marks]
Feb Drive 2011
398, 412, 560, 476, 544, 690, 587, 600, 613, 457, 504, 477, 530, 641, 359, 566, 452, 633, 474, 499, 580, 606, 344, 455, 505, 396, 347, 441, 390, 632, 400, 582
Assume these data represent an entire population. Find the population mean and the population standard deviation.
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