LAB 3 INSTRUCTIONS QUESTIONS FOR EXCEL 2003 NORMAL DISTRIBUTIONS NAME LABTIME BLDG 1 2 3 4 5 6 7 8 9 10 11 12 Open Excel from Microsoft Office 2003 Click on tools macro security and select medium Go to the Stat301T webpage click on Lab Instruction Questions and Data open Lab 3 instructions and questions Save the Normal Table file to your home directory Open the Normal Table file When the window comes up select enable macros You might get a blank gray screen If you do go to the tool bar click on windows and unhide the first sheet You should get a yellow screen that says Probability Calculations Click on Normal You should get a screen showing a normal curve with two z boxes below it You can fill in any z values in the boxes and the template will show the area between the two z values in blue Also the percent of the entire area will be shown If you want to know the percent below a certain z value use a lower value of 5 Likewise use an upper z value of 5 for percents above a given z value The standard normal density curve has a mean 0 and a standard deviation 1 0 Use the template to determine the percent of area between z 2 3 and z 2 3 13 What percent is below 2 3 14 What percent is above 2 3 15 By trial and error find the z value 2 decimal places which is equivalent to the 1st quartile has 25 below it or as close as possible to 25 16 17 The z value for the 3rd quartile has the same value but the sign is positive Enter these two z values and record the percent area between them 18 Other normal density curves require reduction of the boundary values to the equivalent z values using the formula z x To go the other way x z 19 20 SAT Verbal scores in 2000 followed approximately a normal distribution with mean 504 and standard deviation 111 The shorthand designation for this is N 504 111 Find the percent of SAT verbal scores which would be between 400 and 600 Convert the values 400 and 600 to their equivalent z values 2 decimal places enter them in the template and record the percent 21 Find the percent of SAT verbal scores which would be above 700 22 Find the percent of SAT verbal scores which would be below 300 23 Find the percent of SAT verbal scores which would be above 400 24 Find the percent of SAT verbal scores which would be between 300 and 400 25 Use the z value for the 1st quartile from step 15 and the second formula in step 18 to calculate the 1st quartile for the distribution of SAT verbal scores 26 Repeat step 25 to find the 3rd quartile for the SAT verbal scores 27 Close the normal template 28 Save your file Updated on 9 09 08
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