Question

Approximately 1.65 million high school students take the Scholastic Aptitude Test (SAT) each year and nearly 80% of the college and universities without open admissions policies use SAT scores in making admission decisions (College Board, March 2009). The current version of the SAT includes three parts: reading comprehension, mathematics, and writing. A perfect combined score for all three parts is 2400. A sample of SAT scores for the combined three-part SAT are as follows:

1665 1275 1650 1590 1475 1490​
1525 2135 1560 1880 1680 1560
​1355 1280 1150 1420 14409 40​16
4510 6014 8517 5512 6013 90​17
8015 8519 901 3751 7301 1755​

Required:
a. Show a frequency distribution and histogram. Begin with the first class starting at 800 and use a class width of 200.
b. Comment on the shape of the distribution.
c. What other observations can be made about the SAT scores based on the tabular and graphical summaries?

Answer 1

Explanation:

Hello!

The sample shows the scores for the combined three-part SAT.

Raw data in first attachment.

a.

To arrange the data in a frequency table using class intervals you have to determine the number of intervals you want to use and calculate their width. In this case, the width is given and so is the lower limit of the first interval, you calculate the successive limits by adding the width. The lower limit of the next interval will be the upper limit of the previous one:

1) 800 + 200= 100

First interval [800; 1000)

2) 1000 + 200

Second interval

[1000; 1200)

And so on until you reach the maximum value of the data set,

[1200; 1400)

[1400; 1600)

[1600; 1800)

[1800; 2000)

[2000; 2200)

Then you have to order the data from least to greatest and count how many observations correspond to each value, this way you'll determine the observed frequency for each interval.

Table and histogram in second attachment.

b.

As you can see in the histogram, this distribution is symmetrical centered in the interval [1400; 1600) and there are no outliers observed.

c.

Values around 1400-1600 are the most common ones while scores around 800-1000 or 2000-2200 are more uncommon, in this sample it seems the probability to obtain a perfect score for the combined three-part SAT is extremely low.

I hope you have a nice day!