ACT Math Problems Explanations?

Test Preparation ACT Preparation
1

<p>Just took a practice test and there's a few questions that I'm confused about</p>

<ol>
<li>Erin and Amy are playing poker. At a certain point, Erin has three more chips than Amy. On the next hand, Erin wins four chips from Amy. Now how many more chips does Erin have than Amy?</li>
</ol>

<p>Answer is 7
I don't understand why if lets say Erin started with 10 chips and Amy had 7. The problem clearly states Erin took four FROM Amy. So I reasoned Erin has 14 and Amy has 3. My final choice was 11 which was wrong. <---Confused</p>

<ol>
<li>If the first day of the year is a Monday, what is the 260th day?</li>
</ol>

<p>Answer: Tuesday</p>

<p>Is there a math formula out there that can solve this? I tried doodling a calendar in my book wit much failage. </p>

<ol>
<li>If you drive 60 miles at 90 miles an hour, how many minutes will the trip take you?</li>
</ol>

<p>Answer 90</p>

<p>Tried d=r*t didnt work. What would the math setup for this be?</p>

<ol>
<li>On coordinate plane, points P(6,2) and Q (1,4) are two vertices of TrianglePQR. If Angle PQR is a right angle, then which of the following could be the coordinates of R?</li>
</ol>

<p>(Sorry there's no diagram)</p>

<p>Answer: (2,1)</p>

<p>Confused on where to start completely</p>

<p>Any helpful explanations would be awesome. All my other sections on the ACT are in the thirties and math is still slumping be down in the 20's. My composite goal is a 34 so any help or tips would be nice :)</p>

2

<p>ignore the first question, I got it right but read the wrong answer choice </p>

<p>I do have a question on this problem
If the radius of a cone is halved and the height is doubled what will be the new volume to the old volume?</p>

<p>Answer: 1:2</p>

<p>Explanation?</p>

3

<ol>
<li><p>260 is congruent to 1 (mod 7). That is, 260 leaves a remainder of 1 when divided by 7, so 259 days from now it will still be Monday. The 260th day is Tuesday.</p></li>
<li><p>Pay attention to units!
60 mi = (90 mi/hr)(t) → t = 2/3 hr = 40 minutes. Question is screwed up. If it said “90 miles at 60 miles per hour” then it’d be 90 minutes.</p></li>
<li><p>Angle PQR is 90 deg → PQ is perpendicular to QR. The slope of the line through PQ is -2/5 so the slope of QR is 5/2. We know Q is at (1,4) so R lies on the line</p></li>
</ol>

<p>y - 4 = (5/2)(x - 1)</p>

<p>And (2,1) is NOT on that line. Another screwed up question.</p>

<ol>
<li>A = (1/3)(pi*r^2)(h). If you replace r with r/2 and h with 2h you will obtain</li>
</ol>

<p>A_2 = (1/3)(pi*(r/2)^2)(2h) = (1/2)A. The new volume is 1/2 the original volume and the answer is 1:2.</p>

4

<p>wait we have to know the formula for cones? ***</p>

5

<p>I think so…this problem can be solved without the volume of a cone though. But it’s better to know it anyway.</p>

<p>For reference, the volume of a cone with radius r and height h is (1/3)(pi*r^2)(h).</p>