Suppose stock price of a firm is $36, Earnings per share = $4, 
            dividend per share is $1.8, what is the dividend yield?

Fatima1102 --

If the dividend per share is $1.80, then the dividend yield is 5%. 
The dividend yield is the annual dividend(s) divided by the stock
price or $1.80/$36 = 5%.

For definitions of terms like this you can use the define: function in
Google, like this --
define:dividend yield

Best regards,

Omnivorous-GA