In: Statistics and Probability
2. Use the table below to answer the following questions.
| 
 Increase Use of  | 
 Business Focus  | 
||
| 
 | 
 B2B  | 
 B2C  | 
 Total  | 
| 
 YES  | 
 1478 _______  | 
 1027 _______  | 
 2505 _______  | 
| 
 NO  | 
 467 _______  | 
 841 _______  | 
 1308 _______  | 
| 
 Total  | 
 1945 _______  | 
 1868 _______  | 
 3813 _______  | 
Solution:
Given:
| 
 Increase Use of  | 
 Business Focus  | 
||
| 
 | 
 B2B  | 
 B2C  | 
 Total  | 
| 
 YES  | 
 1478 _______  | 
 1027 _______  | 
 2505 _______  | 
| 
 NO  | 
 467 _______  | 
 841 _______  | 
 1308 _______  | 
| 
 Total  | 
 1945 _______  | 
 1868 _______  | 
 3813 _______  | 
Part a) Calculate the joint and marginal probabilities for the data above.
To find joint probabilities , divide each cell frequency by Total 3813 and to find marginal probabilities divide each row total and each column total by total 3813
Thus we get:
| 
 Increase Use of  | 
 Business Focus  | 
||
| 
 | 
 B2B  | 
 B2C  | 
 Total  | 
| 
 YES  | 
 1478 1478/3813  | 
 1027 1027/3813  | 
 2505 2505/3813  | 
| 
 NO  | 
 467 467/3813  | 
 841 841/3813  | 
 1308 1308/3813  | 
| 
 Total  | 
 1945 1945/3813  | 
 1868 1868/3813  | 
 3813 3813/3813  | 
Thus joint and marginal probabilities are:
| 
 Increase Use of  | 
 Business Focus  | 
||
| 
 | 
 B2B  | 
 B2C  | 
 Total  | 
| 
 YES  | 
 1478 0.388 ______  | 
 1027 0.269 _____  | 
 2505 0.657 _____  | 
| 
 NO  | 
 467 0.122 _____  | 
 841 0.221 ______  | 
 1308 0.343 ______  | 
| 
 Total  | 
 1945 0.510 _____  | 
 1868 0.490 _____  | 
 3813 1.000 ______  | 
Part b) What is the marginal probability of Yes increased Use of Linkedin (Yes)?
P(Yes) = .........?
P(Yes) = 0.657
Part c) What is the conditional probability that Yes increased use of Lindedin given a B2C business focus [P(YES | B2C)]?
P(YES | B2C) =..............?
P(YES | B2C) = P( YES and B2C) / P(B2C)
P(YES | B2C) = 0.269 / 0.490
P(YES | B2C) = 0.549
Part d) Are Increase use of Linkedin and Business Focus independent?
P(YES | B2C) = 0.549 and P(YES) = 0.657
Since P(YES | B2C)= 0.549 which is not equal to P(YES)= 0.657, thus increase use of Linkedin and Business Focus are NOT independent.