According to a 2017 Wired magazine article, 40% of emails that are received are tracked using software that can tell the email sender when, where, and on what type of device the email was opened (Wired magazine website). Suppose we randomly select 50 received emails. 

a. What is the expected number of these emails that are tracked? 

b. What are the variance and standard deviation for the number of these emails that are tracked?