If the population of a certain country increases at the rate of one person every 20 seconds, by how many persons does the population increase in 1 hour? Choose the correct answer
A) 100	B) 120	C) 150	D) 180	E) 160
Answer = 3 * 60= 
<gadget id="calculator">3 * 60</gadget>
<output>180</output>
180   Answer is 180
<result>D</result>
If the population of a certain country increases at the rate of one person every 20 seconds, by how many persons does the population increase in 1 hour?