<p>Hi guys,</p>
<p>I noticed after solving many exams I always get 2-3 wrong in inverse and direct proportionality problem and rate problems.</p>
<p>I don't know how to visualize them properly I want to know if there is good tutorial that explain them,also if there something like extensive work out in them,because I need to be able to solve all kind of problems on SAT.</p>
<p>Thanks.</p>
<p>If you have about a year before the SAT, sign up for a physics course. Physics, even physics I, is a great math refresher course. Plus, you learn all about inverse and direct proportions when you talk about gravity, Hooke’s law, etc.</p>
<p>^No I have until October my range in math now is 42 right which is 610-670 I need to get range 700 average.</p>
<p>Have you tried Dr.John Chungs math?</p>
<p>I just got it today, will be testing it out. I got a 630 on my last SAT. Although I am pretty good at math I make too many mistakes on the SAT.</p>
<p>Could you post a problem of this type that you’re having trouble with so that we have a better idea of what’s troubling you?</p>
<p>Direct and indirect proportion are just ways of describing a relationship between variables. </p>
<p>Direct proportion
If x is directly proportional to y, it means that when x increases, y increases at the same rate, so that x/y will always equal the same thing. You can set up the equation</p>
<p>x/y = c </p>
<p>c is a constant. Finding c will help you solve the problem. </p>
<p>Sample question:
If x is directly proportional to y, and x = 24 when y = 6, what is y when x = 36? </p>
<p>To solve, just find c. You know x = 24 when y = 6, so plug in to find that c = 4. That let’s you solve for y when x = 36 by setting up the following equation:</p>
<p>36/y = 4
y =9</p>
<p>Indirect proportion is similar. The only difference, if j is indirectly proportional to k, is that as j goes up, k goes down at the same rate (and vice-versa). So you can set up the equation</p>
<p>jk = c</p>
<p>Sample problem
Integers j and k are indirectly proportional. If j = 20 when k = 5, what is j when k = 50? </p>
<p>To solve, find c: jk = 100, so c = 100. Then plug in what you know</p>
<p>50j = 100
j = 2</p>
<p>Direct and indirect proportion are sometimes referred to as “varies directly” or “varies indirectly,” such as "if x varies directly with k, and x . . . " It means the same thing and you’d solve it the same way. </p>
<p>Hope this helps.</p>
<p>@PrestigePrep</p>
<p>Thanks alot that helped me get the intuition.</p>
<p>@Mariolee</p>
<p>I mean problems where is two variables like X going on same route then returning back at same route what is the distance or questions like</p>