<p>not in the consildated list...probably a stupid mistake...but i am too tired (midnight after a day of mtn biking) to find my mistake .... so here is the question</p>
<p>Pg. 411 #14</p>
<p>The question is:</p>
<p>
[quote]
Exactly 4 actors try out for the 4 parts in a play. If each actor can perform any one part and no one will perform more than one part, how many different assignments of actors are possible?
[/quote]
</p>
<p>Think of it this way: 4 spots right? Spot 1 can be filled by 4 actors, and since Spot 1 is taken, one actor is used, so Spot 2 can be filled by 3 actors, Spot 3 by 2 actors and Spot 4 can only be filled by 1 actor. </p>
<p>So:</p>
<p>4 x 3 x 2 x 1 = 24</p>
<p>the formula for permutation/'arrangement' problems is n! ....in this case 4!(4<em>3</em>2*1)...go to google and type in 'probability,permutations and combinations'.. You'll find like 6 very useful links on the first page of search results. Pick the most comprehensive one and you'll be able to solve these kinds of problems EASILY.</p>
<p>Please help me with this problem. I chose A, but the correct answer is C. I cannot understand why. See here, the general equation for a linear function is
f(x) = y = ax+b
If x=1, f(x)=24
Conclude a+b=24
This problem is in the blue book, official SAT guide; the 12th problem in section 3, practice test 1</p>
<p>X f(x)
0 a
1 24
2 b</p>
<p>The table above shows some values for the function f. If f is a linear function, what is the value of a +b
(A) 24
(B) 36
(C) 48
(D) 72
(E) It cannot be determined from the information given</p>
<p>Since f is linear, its slope is constant, which translates to:
(24 - a) / (1-0) = (b - 24) / (2-1) (Slope formula)
which makes
24 - a = b -24
or
a + b = 48</p>
<p>what is wrong with my solution? Do you know? </p>
<p>See here, the general equation for a linear function is
f(x) = y = ax+b
If x=1, f(x)=24
Conclude a+b=24</p>
<p>It's wrong because your equation, y = ax + b, is incorrect. You are confusing the variables.</p>
<p>The general equation for a line is y = mx + b, where m is the slope, and b is the y-intercept. The variable "b" in the question is not the y-intercept. It is the value of the function f at x=2. The actual y-intercept in this case is a, because at x=0, f = a.</p>
<p>So the correction equation is y = mx + a, where a is the y-intercept and m is the slope. So you would have:</p>
<p>a = m(0) + a
24 = m(1) + a
b = m(2) + a</p>
<p>And solve it from there. Hope this helps.</p>