CSCI A113 Lecture Notes Six Fall 2001

Homework Assignment Three posted, will be discussed in class today. Two new quizzes posted QuizSite, will be discussed in class today as well. I will change these notes and include all the quizzes here tonight for your reference. Here's the first of the two new quizzes, as an example:

Question 1.
Let us suppose that each of 260 students lined up in front of a sign that gave that particular student's weight. The sign running from left to right in order of increasing weight are from 135 to 165 pounds. (The picture below uses Duke, the Java mascot, to illustrate the point, for weights of 149-152 lbs.).

This is only an illustration, but we can see three people (or, rather, dukes) have 149 lbs., 5 dukes have 150 lbs. (one of them is waving), 8 of them weigh at 151 lbs., 5 at 152 lbs., and so forth. Now the question. We say that the number of persons in any one line is the frequency of that weight. Therefore the number of 150 pounders is the of 150 pounders.

---

Question 2.
From an airplane, the place where this odd event was occurring might look like the diagram below.

Each dot represents a

---

Question 3.
Assuming that the students are separated from one another by the same amount of space, the number of cases would be indicated by the area. For example, with 260 cases, the 26 heaviest students would occupy the extreme right 10% of the crowd.

The 13 lightest people would occupy the extreme left percent of the crowd. (Write the percentage in the box).

---

Question 4.
If each column of students is represented by a rectangular box,

we have our old friend the

---

Question 5.
If we have a very large number of people and use very small weight categories, the irregular step-like curve would become smooth and continuous. The resulting figure approaches a special type of curve called the normal curve.

In frequency distributions normality is not associated with small groups of people but rather with very groups of people.

---

Question 6.
In a normal curve (which by definition describes an infinite number of cases) the tails of the curve never touch the baseline. Which curve below could be a true normal curve?

Curve A
Curve B

---

Question 7.
It has been found that quantitative data gathered from hig-frequency random measurements of natural phenomena and of many mental and social traits, even though not precisely normal in distribution, can closely be described by the normal

---

Question 8.
The distribution of such diverse properties as achievement test scores, I.Q., and height and weight of people form approximately curves (or distributions).

---

Question 9.
When a line approaches infinitely close to another line but does not touch that line, the lines are said to be asymptotic. The end points of a normal curve are to the base line.

---

Question 10.
The bell-shaped curve illustrated below approximates what the statisticians call a normal curve.

Note the following properties:

1. It is symmetrical
2. The mean, median and mode have the same value (in this instance, 70)
3. There are thus an equal number of scores on either side of the mean (central axis)
4. It is composed of infinitely large numbers of cases
5. The end points of the curve are to the abscissa (base line).

---

Click "Proceed" to submit your answers.

(Note: this is just a screen shot. Please make sure to take the real quizzes.)

This activity is available between these dates and times: 11.08.08:00-11.20.23:59
It can be submitted a total of 1000 times.
If it is a scored activity, the highest non-zero score will be counted.