how much of pre calculus will be seen on the psat? I will be taking pre calculus this year, and theres are some circle related stuff that I still need to study.
@wildguy57 circles and certain properties (e.g. theorems involving arcs, angles within circles; power of a point) are usually covered in a standard HS geometry course – not so much in pre-calculus.
You can see a list of PSAT math topics here:
https://collegereadiness.collegeboard.org/psat-nmsqt-psat-10/inside-the-test/math
What is the product of (1-p) and [(1/2)-p], all reduced by p?
This is the first time I’ve encountered the term “all reduced.” Does this refer to simple subtraction?
Please tag me when you answer. 
@pizzatom999 does it mean in terms of p? That is the first time I have seen “all reduced by…” and that wording seems pretty awkward. It also doesn’t feel SAT-like.
@MITer94
It’s from the official Khan Prep.
(1−p)⋅(1/2−p)−p was the equation they solved in the given solution, so basically they added a -p to the end of the product. For my answer, it said “You may have forgotten to subtract p from the product.”
My answer was 1/2 * (2p-squared -3p+1) and the correct one was 1/2 * (2p-squared -5p+1)
@pizzatom999 yeah, my first guess was that “all reduced by p” means “subtract p” from the final result. But it sounds too close to “reduced by a factor of p” (which often carries the same meaning as, divide by p).
Assuming they meant subtract p, then yes, (1-p)((1/2) - p) - p = (1/2)(2p^2 - 5p + 1).
Wang Xiu measured the brightness of a glowstick. The equation below models the brightness,L in lumens, h hours after activating the glowstick.
L= 4*0.73^h
Which equation best highlights the number of hours it would take for Wang Xiu’s glowstick to lose 90% of its brightness?
The answer is L=4*0.1^(h/73)
I don’t get how this form highlights “the number of hours it would take for Wang Xiu’s glowstick to lose 90% of its brightness.”
Both of the last two questions are very poorly worded. They would not appear on an SAT.
Consider the parabola whose equation is
y^2 = x^ -2 + 8x + 16
If m represents the number of time the parabola crosses the y axis and n represents the number of times it crosses the x axis what is the value of
m + n?
The answer is 2
M=1
N = 1
While the m part is clear, I’m not sure if n=1 is correct because the parabola merely touches the x axis, i.e. it doesn’t cross the x axis
First, the equation does NOT have a parabolic graph. A parabola has an equation with just ONE square term and NEVER a negative exponent. Second, the answer is wrong - for example, there are two y-intercepts. Third, since the equation does not have a parabolic graph, the question is most likely NOT a valid SAT question.
Correction:
y = x^2 - 8x + 16
I don’t know how I typed this wrong.
Sorry for the inconvenience.
Ok. That makes more sense. Yes - the question is not worded very well. The word “crosses” is misleading. The question should have used a word like “intersects” instead.
quick fundamental question. I do know that whenever you multiply or divide by a negative you change the inequality signs.
y > 2x + c
y < -3x + d
If (1,1) is a solution to this system of inequalities, which of the following is true?
the answer is that d>c
If I multiply the first equation by a negative to flip the signs, is it neccesary to do the same for the second equation as well?
I’m not sure why you would want to negate either inequality - there is no advantage to doing so. That aside, let me just answer your question. The fact you stated is about an individual inequality - it has nothing to do with systems of inequalities. You can negate one of the inequalities or both of them, and you will still have an equivalent system.
Oh okay
When it is 9:00 A.M Eastern Standard time in Boston, it is 6:00 A.M Pacific Standard time in L.A. A plane takes off from Boston at 9:00 A.M. EST and arrives in L.A. at 1:00 P.M. PST. If another plane leaves L.A. at 9:00 A.M. PST and it takes the same amount of time flying to Boston as the first plane took flying to L.A., what would be the arrival time in Boston?
A. 6:00 P.M. EST
B. 7:00 P.M. EST
C. 8:00 P.M. EST
D. 9:00 P.M. EST
I am very confused regarding the problem posted above
Here’s another problem:
In a right triangle, seven times the degree measure of the smallest angle is equal to five times the degree of the middle sized angle. What is the measure of the smallest angle in degrees?
@wildguy for your 1st problem, Boston is 3 hrs ahead of LA, so the first plane leaves Boston at 6 am PST. Now you can compute the actual flight time.
For your second one, the triangle is a right triangle so the smallest and “middle” angles correspond to the two acute angles of the triangle.
I’m having trouble with this one. @DrSteve
“Bill has cows, pigs, and chickens on his farm. The number of chickens he has is four times the number of pigs, and the number of pigs he has is three more than the number of cows. Which of the following could be the total number of these animals?”
(A) 28
(B) 27
© 26
(D) 25