1) the ages of trees in a forest are normally distributed with a mean of 25 years and a standard deviation of 5 years. using the empirical rule, approximately what percent of the trees are between 20 and 30 years old?
2)pizza delivery times at pizza time are normally distributed with a mean time of 27 minutes and a standard deviation of 3 minutes. using the empirical rule, approximately what percent of pizzas are delivered between 24 and 30 minutes?

1) 68%

2) 68%

Step-by-step explanation:

We know the mean and the standard deviation.

The mean is:

The standard deviation is:

The Z-score formula is:

For x=20 the Z-score is:

For x=30 the Z-score is:

Then we look for the percentage of the data that is between deviations from the mean.

According to the empirical rule 68% of the data is less than 1 standard deviations of the mean.  This means that 68% of the trees are between 20 and 30 years old

First we calculate the Z-scores

We know the mean and the standard deviation.

The mean is:

The standard deviation is:

The z-score formula is:

For x=24 the Z-score is:

For x=30 the Z-score is:

Then we look for the percentage of the data that is between deviations from the mean.

According to the empirical rule 68% of the data is less than 1 standard deviations of the mean.  This means that 68% of pizzas are delivered between 24 and 30 minutes

answer: (1,3) (3,-1) (5,-5) ?

step-by-step explanation: