In: Statistics and Probability
Solution:
Given:Sample size=49
a)Frequency is the number of observations in a particular interval.
Percentage frequency distribution=(Frequency*100)/ Total frequency
Let us find the width of interval=Range/Number of desired class groupings
Let us assume number of desired class groupings be 6 and range=Maximum value-minimum value=8.498-8.312=0.186
So width of interval=0.186/6=0.031
In first class interval,the lower class limit is 8.312 and upper class limit is 8.312+0.031=8.343
In second class interval,the lower class limit is 8.344 and upper class limit is 8.344+0.031=8.375 and so on.
The frequency distribution and percentage distribution is calculated as follows.
Class interval | Frequency | Percentage distribution |
8.312-8.343 | 4 | (4/49)*100=8.16 |
8.344-8.375 | 3 | (3/49)*100=6.12 |
8.376-8.407 | 7 | (7/49)*100=14.29 |
8.408-8.439 | 19 | (19/49)*100=38.78 |
8.440-8.471 | 8 | (8/49)*100=16.33 |
8.472-8.503 | 8 | (8/49)*100=16.33 |
Total | 49 |
b)Cumulative percentage distribution=(corresponding percentage frequency)+(Preceding percentage frequency)
The table below shows the calculation of cumulative percentage distribution.
Percentage distribution | cumulative percentage distribution |
8.16 | 8.16 |
6.12 | 8.16+6.12=14.28 |
14.29 | 14.28+14.29=28.57 |
38.78 | 28.57+38.78=67.35 |
16.33 | 67.35+16.33=83.68 |
16.33 | 83.68+16.33=100 |
c)The company requirement that the width of the trough be between 8.31 inches and 8.61 inches is satisfied.
It can be concluded that all the given troughs will meet the requirement of being between 8.31 and 8.61 inches.