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Ex2) The following data represent the top 25 ranked college by SAT scores (out of 2400)

 

1545

1500

1480

1455

1440

1515

1490

1475

1455

1440

1505

1489

1470

1450

1435

1505

1485

1460

1445

1435

1500

1480

1460

1440

1435

 

(a) Construct a frequency, relative frequency distribution, and cumulative relative frequency of data (5 classes).

 

Class Limit

Frequency

R.F

Cum. Freq.

Cum. R. F

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

             

 

 

 

 

 

 

 

 

 

 Total

25

1

25

1

 

asked Jan 31, 2015 in STATISTICS by doan12345 Pupil
reshown Jan 31, 2015 by goushi

1 Answer

–1 vote

Step 1:

The smallest number in data set is .

The largest number in data set  is .

Range =

The range

Class limit

Sample size image

image

image.

Step 2:

Class limit Frequency R.F Cum.frq CumR.F

 image

image

image

image

image

 

image

image

 

image

image

 

image

Total

 

answered Jan 31, 2015 by david Expert
edited Jan 31, 2015 by bradely
How did you find the class width?
For the class width I got

1435-1456

1457-1478

1479-1503

1504-1522

1523-1544

Find the first class limit by adding class width to lowest value.

1435 + 22 = 1457

Second class limit :

1458 + 22 = 1480.

 

The classes must be equal in width.

If you consider class limits :

1435 - 1456

1457 - 1478

1479 - 1503

1504 - 1522

1523 - 1544

The classes are not equal in width.

Find the width of classes.

First class limit 1435-1456.

width = 1456 - 1435 = 21

Third class limit 1479 - 1503.

width = 1503 - 1479 = 24.

In this case class width is not equal, so we don't consider the above class limits.

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