Answer:
B. H0: p1 − p2 ≤ 0; HA: p1 − p2 > 0
 
    

A. Do not reject H0; there is no increase in the proportion of people using LinkedIn
Step-by-step explanation:
1) Data given and notation  
 represent the number of recent jobseekers
 represent the number of recent jobseekers
 represent the number of job seekers three years ago.
 represent the number of job seekers three years ago.
 sample of recent jobseekers selected
 sample of recent jobseekers selected  
 sample of job seekers three years ago selected
 sample of job seekers three years ago selected  
 represent the proportion of recent jobseekers
 represent the proportion of recent jobseekers
 represent the proportion of job seekers three years ago
 represent the proportion of job seekers three years ago
z would represent the statistic (variable of interest)  
 represent the value for the test (variable of interest)
 represent the value for the test (variable of interest)  
 significance level given
 significance level given
2) Concepts and formulas to use  
We need to conduct a hypothesis in order to check if "More people are using social media to network, rather than phone calls or e-mails", the system of hypothesis would be:  
Null hypothesis: 
  
Alternative hypothesis: 
  
We need to apply a z test to compare proportions, and the statistic is given by:  
 (1)
   (1)  
Where  
  
3) Calculate the statistic  
Replacing in formula (1) the values obtained we got this:  
 
    
In order to find the critical value since we have a right tailed test the we need to find a value on the z distribution that accumulates 0.05 of the area on the right tail, and this value is .
.
4) Statistical decision
Since is a right tailed test the p value would be:  
 
  
Comparing the p value with the significance level given  we see that
 we see that  so we can conclude that we have enough evidence to FAIL to reject the null hypothesis.
 so we can conclude that we have enough evidence to FAIL to reject the null hypothesis.
So the correct conclusion would be:
A. Do not reject H0; there is no increase in the proportion of people using LinkedIn