A purch. longevity of the light bulbs used in the projectors. The purchasing manager has narrowed down the choice of projector to two brands, Infocus and Proxima, and wishes to determine if there is any difference between the two brands in the mean lifetime of the bulbs used. manager for a large university is investigating which brand of LCD projector to purchase to equip "smart" classrooms. Of major concern is the The purchasing manager obtained fifteen projectors of each brand for testing over the last several academic terms. The number of hours the bulbs lasted on each of the fifteen machines is given in the table. Lifetimes of light bulbs (hours) Infocus 1091, 818, 1198, 796, 1045, 1084, 1026, 613, 915, 665, 812, 912, 567, 698, 812 Proxima 783, 850, 845, 777, 941, 751, 746, 883, 774, 826, 959, 938, 756, 695, 672 Send data to calculator v Assume that the two populations of lifetimes are normally distributed and that the population variances are equal. Can we conclude, at the 0.01 level of significance, that there is a difference in the mean lifetime of the light bulbs in the two brands? Perform a two-tailed test. Then fill in the table below. Carry your intermediate computations to at least three decimal places and round your answers as specified in the table. (If necessary, consult a list of formulas.) H, :0 The null hypothesis: The alternative hypothesis: H :0 OSO The type of test statistic: (Choose one) v O
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
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