<p>I’ll do number 7: The diameter of the circle is equal to the radius of the semicircle. So the radius of the circle is r/2, and therefore the area of the circle is pi(r/2)^2 = pi r^2/4.</p>
<p>Note: To see that the diameter of the circle is the radius of the semicircle simply draw a line segment from the center of the semicircle to the point on the circle such that the segment forms a right angle with the diameter of the semicircle.</p>
<ol>
<li><p>(r^2)/s is just r/3, and since r is a positive ratio, it can equal any positive multiple of 1/3.</p></li>
<li><p>Move the longest side outward since it increases the area the fastest. Since 20*.2 = 4, you only need to move the 20 m side by .2 m. You will need .2 m for both sides, so the answer is .4 m.</p></li>
</ol>
<p>Here’s #5: The first train has a two-hour head start. At 40 mph, that’s an 80 mile start. The second train is 20mph faster, so it reduces the lead by 20 miles each hour. That means it takes 80/20 = 4 hours which takes you to 5 pm.</p>
<p>I’ll do #2 … So there are 220 stamps of which 60 are US stamps. Minus 60 from 220 to give you 160 non-US stamps</p>
<p>Then it’s says 60% of the US stamps were cancelled. So that means 36 US stamps were cancelled. Minus 36 from 110 which shows that 74 non-US stamps were cancelled </p>
<p>So now they are asking you which stamps were NOT US Stamps and NOT cancelled.</p>
<p>You already know 160 were non-US stamps so minus 74 from 160 which will give you the number of non-US stamps that were NOT cancelled. 86 in this case</p>
<p>I’ll do #3 as well … So basically they are saying that there are 25 squares patented either red, green, yellow or blue and ask you to find out the maximum number of blue squares in such a configuration </p>
<p>They also state some of the conditions that must be satisfied such as having one square of each colour in the row and not having two squares of the same colour side by side</p>
<p>The row to get 13 blue squares would be something like this …</p>
<p>BRBYBGBYBYBYBYBYBYBYBYBYB</p>
<p>Notice that not only do I ensure that two squares of the same colour are not next to each other but also ensure that all 4 colours are represented</p>
<p>OK, #4: To find the average time per question, you divide the time by the number of questions. For Form A, that’s 2m/q. For form B, that’s (3m)/(1/2 q) = 6m/q.</p>
<p>Then, to get the difference, just subtract: 6m/q - 2m/q = 4m/q.</p>