The scores on a test administered to prospective employees are normaly distriuted with a mean of 100 and a standerd deveation of 15.
1. About what precent of the scores are between 70 and 130?
2. About what percent of the scores are between 85 and 130?
3. About what percent of the scores are over 115?
4. If 75 people take the test, how many would you exspect to score lower than 85?
+33665 The graph below shows the cumulative probability (in %) against score for a normal distribution with mean score 100 and standard deviation 15.
The dotted lines mark out scores of 70, 85, 115 and 130.
1. Looks like about 2% of scores are less than 70 (follow the black dotted line from the score of 70 up to the red line and then across to the probability axis), and about 98% in total are below 130. This means that about 98% - 2%, or 96% are between 70 and 130.
Now have a go at the other parts of the question yourself.
+33665 The graph below shows the cumulative probability (in %) against score for a normal distribution with mean score 100 and standard deviation 15.
The dotted lines mark out scores of 70, 85, 115 and 130.
1. Looks like about 2% of scores are less than 70 (follow the black dotted line from the score of 70 up to the red line and then across to the probability axis), and about 98% in total are below 130. This means that about 98% - 2%, or 96% are between 70 and 130.
Now have a go at the other parts of the question yourself.
