Hi There, Anyones help with the below would be appreciated.
"500 students took an exam, the mean was 69 and the standard deviation was 7. if the grades have a mound shape distribution, how many students recieved a grade of more than 83" With my new found knowledge I have tried to work this out as follows. 1.Find the Z-Score, which equals to 2 2.Based on the Empirical rule, approx 95% of values fall within 2 SD's of the mean. Therefore that leaves 5% outside of this, which I have divided by 2 to calculate the SD above the mean. Which gives me 2.5%, so I think 2.5% of students recieved a grade of more than 83. 3. To find convert this from a percentage to the actual amount of students I caluclated as 500*0.025 = 12.5. 12.5 students? eah? I have no idea if the above is correct ( I don't think it is), but it dosen't seem logical that 12.5 students recieved more than 83, as I've never encountered a half person before! I think I've missed something.. If someone could please help I would be very thankful. ~Mel . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
