Standard Deviation, Normal Distribution and the 68-95-99.7 Rule

In this video, Dr. Kushner breaks down standard deviation, and discusses the 68-95-97.7 Rule as a memory technique to identify the %'s on a normal distribution.

📝Practice Question #2 Answer:
Mean: 3.0
SD = .2
Your normal distribution below the mean should be 3.0, 2.8, 2.6, 2.4.
ANSWER: 13.5% + 2.35% + .15% = 16% of students have a GPA lower than 2.8

💻Calculating standard deviation:
Step 1: Calculate the mean (average) of each data set.
Step 2: Subtract the deviance of each piece of data by subtracting the mean from each number.
Step 3: Square each deviation.
Step 4: Add all the squared deviations.
Step 5: Divide the value obtained in step four by the number of items in the data set.
Step 6: Calculate the square root of the value obtained in step five.