Algebra Practice

Test Preparation SAT Preparation
1

<p>Over the last 3 months, the output of a shoe factory decreased by a total of 10 percent. If the output continued to decrease at the same rate for the next 3 months, by what percent would the output have decreased over the entire 6-month period?</p>

<p>A. 5%
B. 10 %
C. 19%
D. 20%
E. 21%</p>

<p>For this question, I know the answer is C and have looked at the working out for it but just can't seem to understand it!! Can someone please explain this to me, I've been trying to figure it out for over an hour! I understand that 10% of x is x/10 but I'm not sure how the 'plugging in' method works for this question. Someone please help me!</p>

2

<p>Let me start with some notes:</p>

<p>(1) In percent problems starting with the number 100 is often the quickest way to get the answer.
(2) Decreasing something by 10% is the same as taking 90% of that thing.
(3) Taking 90% of something is the same as multiplying by the decimal .9.</p>

<p>If you understand these notes, the problem takes a few seconds:</p>

<p>100<em>.9</em>.9 = 81. So the answer is 100 - 81 = 19%, choice (C).</p>

3

<p>^ what I got. Then again who’s to doubt DrSteve lol</p>