# Pointers for passing Praxis 1 Math in GA

Discussion in 'Basic Skills Tests' started by bnewsome, Jul 12, 2006.

1. ### TeacherGroupieModerator

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Jun 5, 2007

No, not an idiot.

Now, can you make that work for you in this question?

If p - 20%p = \$12,590, where can you go from there?

(What Alice meant is that she's a mom, and will drop what she's doing on A to Z when a kid calls - or when it gets ominously silent, whichever comes first.)

2. ### TeacherGroupieModerator

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Jun 5, 2007

That is, what part of p is p - 20%p?

3. ### PraxisManiaRookie

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Jun 5, 2007

Seriously, I just tried to work it out and have no idea. You cannot put 100% in for both p's..it doesn't work.

*Alice I am sorry...you did not have to answer my questions since ur on motherly duty

4. ### TeacherGroupieModerator

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One of them already has a percent: it doesn't need another. But you're on the right track.

5. ### AliceaccMultitudinous

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Jun 5, 2007

Well, I'm pretty much ALWAYS on mom duty; it's not really a part time job. But the younger 2 are in bed (although still awake) and Brian is watching TV... and I don't feel like grading the 2 sets of tests waiting for me. So here I am.

Let me pick up on TG's line of thought:
Change "p - 20%p?" to "100%p-20%p"

What do you get when you take a whole amount and subtract 20% of it? How about when an item is marked "20%off"-- that's 20% off the original 100%, right???

6. ### PraxisManiaRookie

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Jun 5, 2007

since p-20%p...can u switch the formula and make it p=20%p?

7. ### AliceaccMultitudinous

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Jun 5, 2007

Oops, sorry TG-- I thought you had left.

8. ### TeacherGroupieModerator

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I should've left, and am about to...

but, PraxisMania: the only circumstance in which "p - 20%p" means the same thing as "p = 20%p", and in which "p = 20%p" isn't total nonsense, is when p = 0.

Try again, and look at Alice's explanation, please.

9. ### PraxisManiaRookie

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Jun 5, 2007

*Oh I totally understand that being a mom is a full time job. I am one myself..22, single mom of 2yr old, trying to pass praxis..not fun..hence the reason i'm on here so much. Sorry for any inconvience of asking so many questions. I think TG is getting fed up w/ me.

Yes, that is 20% off the original price but I still have no idea on how to subtract percentages for some reason! My previous math background isn't kicking it

10. ### AliceaccMultitudinous

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Jun 5, 2007

Again, a \$100 item is marked 20% off. How much does it cost?

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Jun 5, 2007

80

12. ### AliceaccMultitudinous

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Jun 5, 2007

Great.

Because 100%-20% (of the same number-- that's important) =80%

13. ### IowaLARookie

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Jun 26, 2007

New here, but thought I could help with this problem. I think a better way to set up the equation is as follows. The 20%p is the same as the 12590 in the problem so the equation should be p - 12590=20%p or in math lingo
p - 12590=.2p
Use algebra to solve by combining like terms.

14. ### TeacherGroupieModerator

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Jun 26, 2007

Another perspective - good!

There may be only one correct answer to a math problem, but it's rarely the case that there's only one right way to get there. (Among the great reasons why a first grade teacher should know at least a modicum of algebra is so that, when one of his young charges comes up with a solution method that works but isn't in the teacher's manual, the teacher won't flip out and insist that it's wrong.)

Welcome to A to Z, helno1. Aliceacc teaches high school math, and I'm the monarch butterfly of the teacher-test forums.

15. ### IowaLARookie

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Glad to be here! I am looking forward to helping anyone I can. I went back to school to get my El Ed degree (already had a B.S., Natural Science), so I know what it is like to go back to school and have to pass these tests! I recently graduated and am set to teach this fall.

16. ### Dr3New Member

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Jul 12, 2007

ok hey alicea, im dre,

im trying to join the military.
and i have failed my asvab do too my low algebra knowledge,

i failed algebra 4 times, alredy, in HS

and, i ran into you , because alot of the problems you have answere are on the pratice
!!!!!!!

but, i wouldnt know how to solve if it wasnt for a calculater,!!!!
and i need to learn long division.. so that i can solve with paper and pencil, nothing else,!

so, if theres anything you can say to help id really appreciet,!!!

p,s i wont know how to check 4 your respond,, if you do get this, so,, ill leave my e-m ail
peruvianborder@hotmail.com

17. ### PraxisManiaRookie

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Jul 13, 2007

Probability

Hello,
I need 2 points in order to pass praxis math component. I was wondering if someone could help me to answer 2 questions for me on probability??

A drawer contains 3 brown socks, 4 blue socks, and 3 black socks.
If you pick 2 socks with replacement, what is the probability of picking:
2 blue socks?
1 blue sock, and then one black sock?
2 blue or 1 black sock, in any order?

If you pick out 2 socks without replacement, what is the probability of picking:
2 blue socks?
1 blue sock, and then 1 black sock?
2 blue socks or 2 black socks?
A matched pair?

**The concept of "With" and "Without" replacement totally confuses me**

18. ### IowaLARookie

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Jul 13, 2007

Someone correct me if I am wrong, but I believe the with replacement means the total number of socks will always stay constant. For example, if you pick 2 blue socks you would then replace with 2 blue socks. So for the 1 blue sock and then one black sock the probability would be 4 out of ten for the blue and then 3 out of ten for the black. On the other hand without replacement means that the total would change. So for 1 blue sock the probability would still be 4 out of 10, but then the probability for the black sock would be 3 out of 9 since the blue sock already picked was not replaced.

19. ### PraxisManiaRookie

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Jul 13, 2007

Yes, thats what I thought! I have the answers:
4/25, 6/50, 49/100, 2/15, 2/15, 1/5, 4/15.
I was doing other questions from another section and a few of the answers were wrong, so its possible a few of these could be wrong too. But if I don't know how to do them I don't know if they're wrong or not.
PS: The answers go in the order of the questions!

20. ### IowaLARookie

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Jul 13, 2007

Again someone correct me if I am wrong. When you have two events that are dependent on the first one (usually your "and" problems) you multiply the two probabilities together. For your "or" problems you add the two probabilities together. Also remember to reduce fractions. So:

1. 2/5 (prob of blue sock reduced from 4/10) * 2/5 =4/25

2. 2/5 (prob of blue sock) * 3/10 = 6/50

3.

4. 2/5 * 1/3 (prob of blue sock reduced from 3/9 [one less blue sock to choose from (3) and one less sock total (9) 2/5*1/3=2/15

5. 2/5 (prob of blue sock) * 1/3 (prob of black sock) =2/15

The next two problems require more steps.

6. first figure probability of 2 blue socks-- 2/15
second figure probability of 2 black socks 3/10* 2/9=6/90 or 1/15
2/15 + 1/15= 3/15 or 1/5

7. First figure probability of matching blue pair:
2/15 --2/5 * 1/3 (3/9 chance of pulling out blue sock)
Second figure probability of matching black pair
3/10 * 2/9 =6/90 or 1/15
Third, figure probability of matching brown pair (it is the same as black since there are 3 brown socks as well--1/15
Finally, 2/15 + 1/15 + 1/15=4/15

Hope this helps!

21. ### PraxisManiaRookie

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Jul 17, 2007

Factoring Problems

I am doing factoring. I understand how to factor, I just don't know where to stop.
I have the factor of 210 and I also have the answers: 1, 2, 3, 5, 6, 7, 19, 21, 30, 35, 42, 70, 105, 210.
Is there a trick to know that the largest factor is
(19x21) ? Or a way of understanding where the factoring stops? The gap b/w 7 and 19 is large.

22. ### AliceaccMultitudinous

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Jul 17, 2007

I just PM'd you, but for anyone else out there:

Once you've eliminated a number as a possible factor, you can eliminate all its multiples. So, when you tried 4 and it didn't work, you eliminated 8, 12, 16, and 20. When you eliminated 9, it eliminated 18. That narrows down your list a bit.

23. ### PraxisManiaRookie

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Jul 17, 2007

percentage

I have a percentage question that says:
What is 17% of 40?
I know that you change 17% into a decimal, therefore making it
0.17 x 40. However the answer given is 6.8.
I was wondering why the answer is only moved one space and not 2 since 0.17 is 2 places??

24. ### IowaLARookie

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Jul 17, 2007

when multiplying your answer is actually 680, then move the decimal over 2 for 6.8.

25. ### PraxisManiaRookie

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Jul 17, 2007

is it 6.8 due to multiplying 17 and 40 then moving the decimal places 2 times? I was multiplying 0.17 by 40 and wasn't understanding the 2 decimal places.

26. ### IowaLARookie

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Jul 17, 2007

Sorry if I wasn't clear I will try and set it up for you

0.1 7
X 4 0
_________
0 0 0
+0 6 8 0
-----------
6 8 0
Then move over 2 spaces due to .17 for 6.8

Does that make more sense?

27. ### IowaLARookie

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Jul 17, 2007

Okay the formating got totally screwed up when it went to post. Sorry, I will try to figure out how to make it work to show you.

28. ### IowaLARookie

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Jul 17, 2007

Okay, that seemed to do the trick.

29. ### PraxisManiaRookie

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Aug 18, 2007

Could someone help me w/ this question?

An instrument store gives a 10% discount to all students off the original cost of an instrument. During a back to school sale an additional 15% is taken off the discounted price. Julie, a student at the local high school, purchases a flute for \$306. How much did it originally cost?

30. ### AliceaccMultitudinous

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Aug 18, 2007

I just sent you a PM.

31. ### AliceaccMultitudinous

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Aug 18, 2007

"per cent" means "divided by 100." In our number system, dividing by 100 means 2 decimal places (dividing by 10 is the 1st).

so 8%= 0.08
12 %= 0.12
25.5%= 0.255

From percents to decimals, it's always 2 places.

32. ### PraxisManiaRookie

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Aug 18, 2007

How many cubed pieces of fudge that are 3 inches on an edge can be packed into a Christmas tin that is 9 inches deep by 12 inches wide by 8 inches high with the lid still being able to be closed?

33. ### PraxisManiaRookie

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Aug 18, 2007

I got your PM, thanks!! I PM'ed you back w/ the problem I had.

34. ### PraxisManiaRookie

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Aug 18, 2007

I don't know how to fit the 'difference' into this problem.

Sarah is twice as old as her youngest brother. If the difference between their ages is 15 years. How old is her youngest brother?

35. ### AliceaccMultitudinous

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Aug 18, 2007

Let x= brother's age.
then 2x= Sarah's age.

If the difference is 15, then the older - the younger= 15.

2x-x=15.
x=15.
Brother is 15. (They didn't ask, but Sarah is 30)

36. ### PraxisManiaRookie

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Aug 18, 2007

Oh ok, I get it now. Thanks, I didn't think of it that way for some reason.

37. ### AliceaccMultitudinous

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Aug 18, 2007

Whenever they use "cubed", it's a clue that you're talking about volume.

Volume of a box = length x width x height
= 9x12x8
=864 cubic inches.

Volume of each piece of fudge= 3x3x3=27

864/27 = 32 pieces.

(We brought some fudge home from vacation and I just had some...yummy )

38. ### PraxisManiaRookie

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Aug 18, 2007

If 5 ounces is equal to 140 grams, then 2 pounds of ground meat is equal to how many ounces?

*Should this question say how many 'grams' and not how many 'ounces'?

39. ### TeacherGroupieModerator

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Aug 18, 2007

Possibly, though it's equally possible that the testmaker was being cute.

First, let's take the problem as stated. In that case, the number of grams per five ounces is irrelevant. 2 lb x 16oz/lb = 32 oz.

Now let's take the problem with the suggested emendation. Here, a proportion can be helpful:

5 oz = 2 lb
40 g = x

One needs to convert ounces to pounds or pounds to ounces before proceeding. In this case, it's easier to work with ounces:

5 oz = 32 oz
40 g = x

Now one can do the traditional cross-multiplication

5x = (32)(40)g = 1280g
x = 256g

Or one can look for patterns in the numbers: it turns out that 40 = 5 x 8, so x will be 32 x 8, which is indeed 256.

40. ### AliceaccMultitudinous

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Aug 18, 2007

Yes, it should probably say grams.

Just about any time they use 2 (or more) different units of measure (here ounces/pounds and grams), you're dealing with a proportion

For starters, let's change those 2 pounds of ground meat to 32 ounces. (16 ounces =1 lb, 32 ounces=2 lb)

Proportion: ounces/grams:
5/140 = 32/y
cross multiply: 140(32)=5y
4480=5y
896=y

896 grams.