PSAT help

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I need help on these problems:
I have no idea how to do them


1.
Let the operation @ be defined for all integers r and s by r @ s = s What is the value of 2 @ (3@4)? Answer is 4


2. If a = x-3, what does x sq. -9 equal, in terms of a? Answer is
a (a +6)


3. WXYT is a square and triangle TYZ is an equilateral triangle. If WXYT has area 1, what is the area of triangle TYZ? Answer is root 3 / 4

4. On Tuesday Jerry studied twice as longas he studied on Monday. On Wednesday he studied 3 hours less than the number of hours he studied on Monday and Tuesday combined. If he studied for a total of 9 hours on the 3 days and x represents the number of hours he studied on Monday, what equation could be used to find the value of x? Answer 6x-3=9

5. If the positive number m is 125% of p, and if p is 60% of k, then m is what percent of k? answer is 85%


6. What is the least positive integer x such that x squared is greater than or equal to 95? Answer: 10

7. The probability of picking a blue marble at random out of a bowl containing 800 marbles is 3/16. how many marbles in the bowl are not blue? Answer 650
 
Why were you given 7 problems and you have "NO IDEA" how to
do any of them?
Is your teacher being mean or something?

Take this one:
6. What is the least positive integer x such that x squared is greater than or equal to 95? Answer: 10

That's quite simple: what do you not understand?
 
Why were you given 7 problems and you have "NO IDEA" how to
do any of them?
Is your teacher being mean or something?

Take this one:
6 such that x squared is greater than or equal to . What is the least positive integer x95? Answer: 10

That's quite simple: what do you not understand?
Click to expand...

ITS NOT AN ASSIGNMENT!!! my teacher didnt asign it. the title does say PSAT! its practice! and FYI i DON'T have a clue how to do this crap... I don't understand how to show the work
 
1.
Let the operation @ be defined for all integers r and s by r @ s = s What is the value of 2 @ (3@4)? Answer is 4
Click to expand...
Answered here.

2. If a = x-3, what does x sq. -9 equal, in terms of a?
Click to expand...
x = a+3
So x^2 = (a+3)^2 = ? <- note that this is a quadratic (and a perfect square to be more specific)
See how you go with this one.

3. WXYT is a square and triangle TYZ is an equilateral triangle. If WXYT has area 1, what is the area of triangle TYZ?
Click to expand...

The square looks like
Code: 
   W +----------+ X
     |          |
     |          |     1 
     |          |
   T |__________| Y
            1
(Area = width^2 <-> 1 = w^2 <-> w = 1)

The equilateral triangle has one side TY, so that side's length is 1 and hence so are it's other sides.
Code: 
          Z
                
  1      / \    1
      /      \
    /___________\
 T        1        Y
Area of a trangle = 1/2 * vertical height * width.

The vertical height is given by
Code: 
        Z       
  1   / |
     /  | h  
   /____|
T   0.5
By Pythagoras, 1^2 = 0.5^2 + h^2
h^2 = 1 - 0.25 = 0.75 = 3/4
So h = sqrt(3)/(sqrt(4) = sqrt(3)/2

So area of the TYZ triangle:
A = 1/2 * sqrt(3)/2 * 1
A = sqrt(3)/sqrt(4)
A = sqrt(3)/2
A = 0.866...

Hopefully this is making sense.

I need sleep :|.
 
4. On Tuesday Jerry studied twice as long as he studied on Monday. On Wednesday he studied 3 hours less than the number of hours he studied on Monday and Tuesday combined. If he studied for a total of 9 hours on the 3 days and x represents the number of hours he studied on Monday, what equation could be used to find the value of x? Answer 6x-3=9
Click to expand...
You're told to let x be the amount of studying on Monday.

"On Tuesday Jerry studied twice as long as he studied on Monday"
... on Tues he studied for 2*x = 2x hours

"On Wednesday he studied 3 hours less than the number of hours he studied on Monday and Tuesday combined"
.. on Wed he studied (x + 2x) - 3

" If he studied for a total of 9 hours on the 3 days, what equation could be used to find the value of x?"
What do you think?

7. The probability of picking a blue marble at random out of a bowl containing 800 marbles is 3/16. how many marbles in the bowl are not blue?
Click to expand...
If I have 10 marbles in a bag, and I know the probability of randomly selecting a blue marble is 2/5, how many blue marbles are in the bag? 2/5 of the marbles are blue, so I must have (2/5)*(total number of marbles) = 2/5 * 10 = 4 blue marbles.
What's the probability of a marble not being blue: 1 - 2/5 = 3/5. 3/5 of 10 marbles is 6 non-blue marbles.

Have a go at the quoted question.
 
alohagrlxo said:
ITS NOT AN ASSIGNMENT!!! my teacher didnt asign it. the title does say PSAT! its practice! and FYI i DON'T have a clue how to do this crap... I don't understand how to show the work
Click to expand...
Well, I don't know how to explain "crap"...
PSAT means practice? Practice SATurday?
 
PSAT is a short name for PSAT/NMSQT, which stands for
Preliminary Scholastic Aptitude Test/National Merit Scholarship Qualifying Test

Just something that we have in United States, and that we have to take in 11th grade (at least in my school).
This test consists of 5 sections (2 math, 3 reading/writing) and is 2 hours and 40 minutes long.

The purpose of the test if to reveal how good you are going to do on the real SAT (which is twice longer), and whether your score is high enough to qualify for a scholarship...
 
5. If the positive number m is 125% of p, and if p is 60% of k, then m is what percent of k? answer is 85%

These problems can be easier if you pick actual numbers. As soon as percents are involved, make some number equal to 100.
Since m is 125% of p, I'll let p = 100, then m = 125
p = .60K, so 100 = .60k Divide both sides by .60 to find k.
Then work out 125 / k


7. The probability of picking a blue marble at random out of a bowl containing 800 marbles is 3/16. how many marbles in the bowl are not blue? Answer 650

The probability that something will happen + the probability something will NOT happen always adds up to 1. 3/16 blue means 1 - 3/16 = not blue
(13/16) * 800 = ?
 
If you think so low of the problems to call them crap, then I could care less about helping you! Think before you write!
 
If you think so low of the problems to call them crap, then I could care less about helping you! Think before you write!
Click to expand...

okay, why are you posting at all if you're not going to help? I thought posting was for people who have questions or people that needs help.
 
No, I was just informing you that in the future don't start off with swear words, that's all. Good luck! :)
 
alohagrlxo said:
does anyone know how to do #6??
Click to expand...
You having the answer readily available spoiled the fun! Not to mention Denis did cover it.
alohagrlxo said:
6. What is the least positive integer x such that x squared is greater than or equal to 95?
Click to expand...
The positive integers are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, ..............

All we are doing is finding the first of these numbers to have a square which is greater than or equal to 95.
What's 5^2? 25 too low
What's 8^2? 64 still too low
What's 9^2? 81 hmm getting close
What's 10^2? 100 ahh that's the first positive integer whose square is greater or equal to 95.
 
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