<p>All right, this question has really been confusing me, and i just can't figure it out.</p>
<p>If w + x + y + z = 12 and the average (arithmetic mean) of w and z is 4, what is the average of x and y?</p>
<p>(A) 2
(B) 3
(C) 4
(D) 6
(E) 8</p>
<p>It is problem number 13 on the October 2007 PSAT.</p>
<p>is the answer A?</p>
<p>Is this the #13 on the Saturday PSAT? cuz it's not on mine
if you got the score report, you should be able to see the answer and explanation online on collegeboard. </p>
<p>btw hpa10, it is A</p>
<p>^ thanks just wanted to make sure if i got it right before trying to explain it to the op, in case he or she still wants an explanation.</p>
<p>w+x = 8, because the average is 4 (w+x/2=4, w+x is 8). that means y+z is 4. 4/2 is 2.</p>
<p>If w + x + y + z = 12 and the average (arithmetic mean) of w and z is 4, what is the average of x and y?</p>
<p>(A) 2
(B) 3
(C) 4
(D) 6
(E) 8</p>
<p>The average of a group of numbers is (sum of the numbers)/(# of numbers)</p>
<p>So the average of two numbers, w and z, is (w + z)/2. But it is also given as 4, so set (w + z)/2 = 4. Thus w + z = 8. </p>
<p>But we also know that w + x + y + z = 12. Substitute 8 in for w + z and you'll find that x + y = 4.</p>
<p>You know the sum of x and y, 4, so the average of x and y is 4/2 = 2.</p>
<p>I can't remember if I answered this correctly on my PSAT, but it's scary how much easier it seems with all the prepping I've been doing during Christmas break. I just wish that I could retake that PSAT and take the October 2007 SAT(I took it from a friend and got a 730 on the math! I really missed out on it!).</p>
<p>Thanks for the help.</p>
<p>It's safe to assume that
w = z = 4
and
x = y = m (mean, or average)
8 + 2m = 12
m = 2.</p>