Normal distribution.

Apr 2010
9
0
1. The following graph of a normal distribution has a mean of 75 and a standard deviation of 5.
8-4_quiz_curve6_cbel.gif

which of the following apply to how the shape and location of the curve would change if the mean becomes 80 and the standard deviation changes to 3.

shifted left
shifted right
narrower
broader
same location
same shape

2. The following graph of a normal distribution has a mean of 20 and a standard deviation of 5.
8-4_quiz_curve1_cbel.GIF

What percent of the data lies between 15 and 25?


3. The following graph of a normal distribution has a mean of 8 and a standard deviation of 1.5.

8-4_quiz_curve2_cbel.GIF

What percent of the data is greater than 6.5?
 
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mr fantastic

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1. The following graph of a normal distribution has a mean of 75 and a standard deviation of 5.
View attachment 16823

which of the following apply to how the shape and location of the curve would change if the mean becomes 80 and the standard deviation changes to 3.

shifted left
shifted right
narrower
broader
same location
same shape

2. The following graph of a normal distribution has a mean of 20 and a standard deviation of 5.
View attachment 16824

What percent of the data lies between 15 and 25?


3. The following graph of a normal distribution has a mean of 8 and a standard deviation of 1.5.

View attachment 16825

What percent of the data is greater than 6.5?
1. The normal distribution is centred on the mean, the sd affects its width ....

2. Look up your book for the rule of thumb for the probability of being within 1 sd of the mean.

3. Use the symmetry of the distribution and the answer to Q2.

(Note: Q2 and Q3 can be done more accurately using Z = (X - mu)/sigma and refering to a standard normal distribution table).