Question

In 4 to 5 sentences post your reply to the following questions:

In life, there are certain variables that are normally distributed. In other words, these variables would produce a symmetric, unimodal, and bell-shaped (normal) population histogram. This means that most of the individual values are close to the mean (average) and that the number of values that are less than the mean is approximately equal to the number of values that are greater than the mean. The further away from the mean, the less number of values there are. There are relatively very few extremely low values and relatively very few extremely high values.

Describe a real-life variable that would produce a symmetric, unimodal, and bell-shaped (normal) population histogram. In other words, let’s say you collected data on the population of the United States. Which variable do you think would produce a symmetric, unimodal, and bell-shaped (normal) population histogram as described above? Why?

For example, my Primary Post would be:

Hello,

My variable would be Height.

Reason: Most of the people in a certain population are of average height. The number of people taller than the average height is approximately equal to the number of people shorter than the average height. Also, a very small number of people are either extremely tall or extremely short."

Answer 1

IQ scores of the population will resemble a normal distribution curve. Although the mean and standard deviation might differ from test to test.

Reason : Most of the population have an IQ of around 100 (85-115 is considered average according to some tests).  An IQ below 85 or above 115 (standard deviation =15) starts becoming less frequent than the average range and lies approximately equally on both sides of the average.  Even rarer is an IQ below 70 (classified as mentally retard) or above 130 (classified as highly gifted), constituting about only 2% of the population on each side of the average.