. Students in a primary school are being tested to see how good their fine motor skills are. The teachers need to order some new equipment so they need an idea of the dexterity of the students. Using a standard dexterity test points, which are normally distributed with a population mean of 14 points and standard deviation of 4.6 points. If a randomly selected individual takes the
Q1. Students in a primary school are being tested to see how good their fine motor skills are. The teachers need to order some new equipment so they need an idea of the dexterity of the students. Using a standard dexterity test points, which are
Q2: According to the American Automobile Association (AAA), the average cost of a gallon of regular unleaded fuel at gas stations in August 2010 was $2.58. Assume that the standard deviation of such costs is $0.15. Suppose that a random sample of n = 100 gas stations is selected from the population and the cost per gallon of regular unleaded fuel is determined for each.
What is the approximate probability that the sample has a mean fuel cost that exceeds $2.7 and between $2 and $3?
Q3. The lengths of stay (in days) for 100 randomly selected hospital patients are mentioned in the excel file (Title: HOSPLOS) available in the Blackboard. The hospital from where this sample has been taken wants to estimate the true mean length of stay (LOS). Form 95% and 99% confidence intervals.
Q4. Most water treatment facilities monitor the quality of their drinking water on an hourly basis. One variable measured is pH, which measures the degree of alkalinity or acidity in the water. A pH below 7.0 is acidic, one above 7.0 is alkaline, and a pH of 7.0 is neutral. One water-treatment plant has a target pH of 8.5. (Most try to maintain a slightly alkaline level) The mean and standard deviation of 1 hour’s test results based on 49 water samples at this plant are: = 8.42; s = 0.16
Does this sample provide sufficient evidence that the mean pH level in the water differs from 8.5?
Q5. Look at the MS Excel file (titled “Easy_Tough”) available in the Blackboard. This file carries data about average MathSAT scores of 297 colleges and universities located in the USA and they are all classified into two groups of colleges and universities. One group of institutions are tough to graduate for students and another group of institutions are easy to graduate for students. Using MS Excel, perform analysis of variance test to examine whether the mean MathSAT score between these two groups are same or not.
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