Thread: Two questions: Histogram and normal distribution.

Another set of questions since mathematics really isn't my area... Sorry, but I need help again.

In a frequency distribution histogram, if I've to list the frequency of each occurring number from 1 to 7, but the frequency for 5 = 0, should I leave a blank area on the histogram or just half the height and double the width for a 4 -> 6 bar?

Normal distribution
Mean: 100
Standard deviation: 20

1. What score separates the top 40% from the bottom 60% of the distribution?
2. What is the minimum score needed to be in the top 5%?
3. What scores form the boundaries for the middle 60%?

Being sick really isn't helping me here. My eyes are watery and blurry and I've to hold a tissue to my nose half the time.