Response/opinion to probability post | MATH 311 – Probability and Statistics I | Liberty University

“A contingency table provides a way of portraying data that can facilitate calculating probabilities (Holmes, A., Illowsky, B., & Dean, S. 2017)”. I was unable to survey half and half, however, I was pretty close. I learned that right handed people far outweighed left handed people. 

Part 1: A survey of 30 people to find out if they are left-handed or right-handed 

Table 1: Contingency table 

                   Left-handed     Right-handed     Total 

Female        5 (A)                 11 (B)                   16(A+B)

Male            3 (C)                 11(D)                    14 (C+D)

Total            8(A+C)              22(B+D)               30(A+B+D)

Part 2 

 A. If a person is randomly selected from the survey participants, what is the probability that the person will be left-handed? 


(A+C)/(A+B+C+D): 5/30 = 0.167 

B. If you randomly choose a female from the people you surveyed, what is the probability that she is left-handed?


A/(A+B): 5/16 = 0.313 

C. What is the odds ratio of choosing a left-handed female? 


PROBABILITY 3 AD/BC: (5*11)/(11*3) = 55/33 = 1.667 

D. What is the relative risk of choosing a left-handed female?


[A/(A+C)]/[B/(B+D)]: (5/8)/(11/22) = 0.625 

Part 3:

According to Orr (2001), the percentage of left-handed people ranges between 10% and 13% of the world population. At one time, being left handed was often treated as a disorder. Teachers and parents would force children to transition into using their right hands. 


Orr, T. (2017). Being a lefty is all right. Current Health, 28(2), 12-13

Holmes, A., Illowsky, B., & Dean, S. (2017). Introductory business statistics. OpenStax.