230 LINEAR REGRESSION AND CORRELATION Ch. 7 



REVIEW PROBLEMS 



1. Define the term percentile and explain how it can be associated with the 

 relative cumulative frequency distribution of a group of measurements. 



2. Calculate the arithmetic mean, standard deviation, and coefficient of varia- 

 tion for the following data on the carotene content of pasture grasses, in milli- 

 grams per gram : 



X: 0.22 0.13 0.23 0.36 0.44 0.26 0.11 0.23 0.26 

 0.26 0.20 0.16 and 0.20 



3. What is the median carotene content for the data of problem 2? The 

 mean deviation? 



4. Compute the geometric mean of 32 and 90. Of 2, 7, and 30. Of the X's 

 of problem 2. Ans. 53.8; 7.49; 0.22. 



5. You are given the following information regarding a group of 2000 weights 

 (in grams) : /jl = 800, md = 700, Q 1 = 500, Q 3 = 900, extreme weights are 350 

 and 1300; and the upper limits of the 15th, 35th, 80th, and 90th percentiles are 

 400, 540, 950, and 1050, respectively. Sketch a graph of the r.c.j. curve. 



6. Given the following scores made on an Ohio Psychological Test, construct 

 a frequency distribution with equal class intervals and compute n and a. These 

 scores are necessarily integers. 



50 65 37 76 82 100 48 69 47 54 33 35 61 74 37 37 

 35 42 128 35 47 57 59 46 91 80 81 78 74 53 39 66 



