## Question 318:

1## Answer:

No answer provided yet.First thing you should notice that both values are less than the mean, so we should expect negative z-scores and areas less than 50%. You'll need to find two areas under the normal curve given the mean of 61.3 and standard deviation 3.3.

- Find the normal deviate or z-score for the larger value : (60-61.3)/3.3 = a z-score of -.3939.
- Find the area under the normal curve using the z-score to percentile calculator, choose 1-sided area. This provides an area of about 34.68%.
- Subtract the smaller area, which following the same steps above is (55-61.3)/3.3= -1.909 and has area of ~2.82%. Subtracting the smaller gets us 34.68-2.82 = 31.9%

So the probability a car is going between 55 and 60 miles an hour is about 31.9%. 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 61.3 and SD of 3.3.