Posted by **Sue** on Wednesday, April 20, 2011 at 4:20pm.

length of time in minutes required to complete exercises is distributed with a mean of 60 minutes and a std. deviation of 8 minutes. what percent will require between 60 and 76 minutes to complete the exercises? what percent of participants will require more than 72 minutes to complete th exercises? what percent will require between 50 and 72 minutes to complete the exercises?

- Statistics -
**MathGuru**, Wednesday, April 20, 2011 at 7:25pm
Use z-scores and a z-table to find your percentages.

Let's look at the very last question and then see if you can figure out the other two questions.

Find two z-scores using this formula:

z = (x - mean)/sd

mean = 60

sd = 8

x = 50, 72

Therefore:

z = (50 - 60)/8 = ?

z = (72 - 60)/8 = ?

I'll let you finish the calculations.

Once you have the z-scores, check a z-table for the probability between those two scores. Once you have that value, convert to a percent.

I hope this will help get you started.

## Answer this Question

## Related Questions

- Math - The mean time to complete a certain stat quiz is 25 minutes, with a ...
- statistics - the scheduled commuting time on Long Island Rail Road from Glen ...
- statistics - Times for a surgical procedure are normally distributed. There are ...
- Probability - The time required for a citizen to complete the 2000 U.S. Census "...
- Statistics - The time to fly between New York City and Chicago is normally ...
- statistics - The times taken to complete a statistics test by all students are ...
- statistics - The times taken to complete a statistics test by all students are ...
- statisticss - The time taken by a man to deliver milk is normally distributed ...
- Q Research - 2. The average commute time via train from the Chicago O'Hare ...
- stat - The average commute time via train from the Chicago O'Hare Airport to ...