<p>I have two problems I need help with from BB2. As stated in the title, these types of problems drive me nuts. Help would be greatly appreciated.</p>
<p>Test 1, section 7, problem 16 (page 418)
A four-digit integer, WXYZ, in which W, X, Y, and Z each represent a different digit, is formed according to the following rules.</p>
<ol>
<li>X = W + Y + Z</li>
<li>W = Y + 1</li>
<li>Z = W - 5</li>
</ol>
<p>What is the four digit integer?</p>
<p>And my next problem: Test 7, section 3, problem 8 (page 770)</p>
<p>I can't really copy the problem because it has a table, but help from those willing to look in their BB2's would be nice.</p>
<p>I just did this on my practice test yesterday haha.</p>
<p>Anyway, your best bet is to plug in some numbers until you get something that works. Here’s how I did it:</p>
<p>Leave the first rule for last since it is the most ‘complicated’. Let’s start with W. I said that W = 6, which means that Y = 5. Moving to rule 3, Z must be 6-5 or Z = 1. This gives me an X value of 12, which is impossible. This means that I want X to be a smaller number. The only way this can happen is for Z to be 0.</p>
<p>I now said that W = 5, so Z = 0 (Rule 3). This means that Y = 5 +1 or Y = 6. This makes X = 9, which is just what I am looking for.</p>
<p>WXYZ will then give me 5940, which is the answer. I hope that makes sense to you.</p>
<p>The table tells us that there are 12 students in the class (3+6+2+1). Let’s go ahead and write out the siblings per student (12) now:</p>
<p>0 0 0 1 1 1 1 1 1 2 2 3</p>
<p>From this, we see that the median number of siblings is currently 1. We want this to be equal to the average number of students per sibling. Currently, the average is 13 siblings for 12 students (13/12). We want the average to be 13/13 or 1, which is equal to the median.</p>
<p>In order for this to happen, the number of siblings of the new student must be 0, or choice A)</p>
<p>For the 4 digit problem, I’m not sure how I did it (the second time I tried it, while taking the test I couldn’t get it) I remember getting one variable and finding what is was = to in terms of all the others. I’m not sure which one it was, but for example it would be something like:
a= b + c - d a = 2c-b a = c+d
And then you would set them equal to each other. I know this works on this problem so just try to find one variable you can set in terms of all the other variables.</p>
<p>you need to realize that X has to be less than 10 in order to make wxyz a 4 digit integer. That greatly focuses guessing and checking. After realizing this it is easy. On seemingly complex problems, there always is an easier method.</p>
<p>the way i did the first problem was to take the 3rd equation and plug in either 5 or 6 (because Z can’t be a negative number),
then plugging the 5 or 6 into the 2nd equation to find out what Y is.
Then plug Y and W into the first equation
you will discover that 6 will make W a double digit number so 5 is the correct value for W</p>