The scores on the Webster test are approximately normal with u=100 and o=15. The proportion of adults with scores between 90 and 110 is closest to??

Z = (score-mean)/SD

After calculating the Z scores, find table in the back of your statistics text labeled something like "areas under normal distribution" to find the related proportion.

To find the proportion of adults with scores between 90 and 110 on the Webster test, we need to calculate the area under the normal curve between these two scores.

First, we need to standardize the scores by using the z-score formula:
z = (x - μ) / σ

where:
- x is the score value
- μ is the mean of the distribution (u = 100 in this case)
- σ is the standard deviation of the distribution (o = 15 in this case)

For the lower bound of 90:
z1 = (90 - 100) / 15 = -2/3

For the upper bound of 110:
z2 = (110 - 100) / 15 = 2/3

Next, we need to find the area under the normal curve between these two z-scores. This can be done using a standard normal distribution table or a statistical calculator.

Alternatively, we can use a statistical calculator like Excel or Python to find the proportion directly using the cumulative distribution function (CDF) of the standard normal distribution.

Using Python, we can calculate the proportion as follows:

```python
import scipy.stats as stats

lower_bound = (90 - 100) / 15
upper_bound = (110 - 100) / 15

proportion = stats.norm.cdf(upper_bound) - stats.norm.cdf(lower_bound)
```

Running this code will give us the proportion of adults with scores between 90 and 110 on the Webster test.

Note: The exact proportion might differ slightly due to the approximation used in statistical tables and calculators, but it should provide a good estimate.