Log-in | Contact Jeff | Email Updates

Question 289:



No answer provided yet.

You'll need to find two areas under the normal curve given the means of 90 and 109 and standard deviation 15. First find the normal deviate or z-score for the larger mean: (109-100)/15 = a z-score of .6. Now, find the area under the normal curve using the z-score to percentile calculator, choose 1-sided area. This provides an area of about 72.5%.  Now we subtract the smaller area, which following the same steps above is (90-100)/15= -.6667 and has area of ~25.2%. Subtracting the smaller gets us 72.5-25.2 = 47.3

So the average region of IQ scores between 90 and 109 has a about a 47.3% probability of being selected.  You can also visualize this area by taking a look at the interactive graph of the standard normal curve and enter in the IQ mean of 100 and SD of 15.

Not what you were looking for or need help?

Ask a new Question

Browse All 869 Questions

Search All Questions: