Ann invested a certain sum of money in a bank that paid simple interest. The amount grew to $240 at the end of 2 years. She waited for another 3 years and got a final amount of $300. What was the principal amount that she invested at the beginning?  Choose one.
A) $200	B) $150	C) $210	D) $175	E) Insufficient data
Answer   The sum grew to $240 at the end of 2 years.   At the end of another 3 years, the sum grew to $ 300.   i.e. in 3 years, the sum grew by $ 60.   Therefore, each year, it grew by $ 20.   Sum at the end of 2 years = $ 240   Sum grew by $ 20 each year.   Hence, in the first 2 years, sum grew by  2 * 20= 
<gadget id="calculator"> 2 * 20</gadget>
<output>40</output>
$ 40.   Therefore, sum at the beginning of the period= Sum at the end of 2 years - $40 = $ 240 - $ 40 = $ 200.   choice is ($200)
<result>A</result>
Ann invested a certain sum of money in a bank that paid simple interest. The amount grew to $240 at the end of 2 years. She waited for another 3 years and got a final amount of $300. What was the principal amount that she invested at the beginning?