Discussion in 'Basic Skills Tests' started by bnewsome, Jul 12, 2006.
Aug 18, 2007
TG-- it was 140, not 40, right?
Yea, the answer key says 896..but it says ounces. Assuming just a typo. When I did it I got 896 as well but I couldn't understand why it was in ounces.
Oooooops. Well, that explains why my number was no good.
Can you check this one out?
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?
Let's take the problem with the suggested emendation. Here, a proportion can be helpful:
5 oz = 2 lb
140 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
140 g = x
Now one can do cross-multiplication
5x = (32)(140)g = 4480g
x = 896g
I did that one... post #77. Was my answer wrong (again) or did you miss it?
Just doing penance...
I apologize for driving you crazy with the tons of questions I'm asking but these are questions I've tried to figure out 100 times and cannot get and Praxis is Wednesday!
According to the answer key the answer from post #77 question is 24. Another possible typo?
Another way to handle this is to realize that, if the pieces of fudge are 3 inches on an edge, one can fit them three deep (9"/3" per piece = 3 pieces) and four across (12"/3" = 4 pieces)... but only two high (8"/3" = 2 pieces). 3 x 4 x 2 = 24 pieces.
OK, I quit. I have vacation brain and it won't go away.
Hopefully the real Alice will return tomorrow.
Have a nice end of vacation, Alice.
Aug 19, 2007
Does anyone have any pointers or rules for percentage problems and geometry problems??
I'm Canadian, therefore no SAT books available. I do have 2 middle school text books, praxis book, and 3 other math books.
Can't you order from Barnes and Noble?
The test is Wednesday...kinna late now
I didn't know about that interest formula....thanks!
If Sam can do a job in 4 days that Lisa can do in 6 days and Tom can do in 2 days, how long would the job take if Sam, Lisa, and Tom worked together to complete it?
In this question I set up all the people being x/# of days.
Multiplied by 24
x=2....which is not the right answer
Do you know where I went wrong?
Ohhh...I worked it out again and got the right answer
Is there a formula for profit?
One that could fit a question such as this:
After purchasing a flat screen television for $750, John realizes that he got a great deal on it and wishes to sell it for a 15% profit. What should his asking price be for the television?
Profit is just a percent... he wants his "price" to be 115% ( or 1.15 times) the original price.
Sep 4, 2007
Are you allowed to discuss actual questions? If not, do you want to edit that post out? I'll PM you with how to solve it.
I didn't even think about that. Yes I probably shouldn't post actual questions. Oops!!
That's OK-- it was up for, what, 10 minutes?
I don't even think it was up that long. I deleted it as soon as you mentioned it.
This is just a random question I found w/in my Praxis material.
If 8 people can sew a quilt in 12 days,
how many people would it take to sew the same quilt in 16 days?
I worked it out this way:
Apparently I have done it wrong. Anyone know what I have done wrong?
Sep 5, 2007
First, the problem you've solved is something like "If 8 people can sew 12 quilts, how many people can sew 16 quilts?" That is, you have to account not just for time but also for people - and we're dealing with a maximum of one quilt.
In any case, the answer has to be fewer than 8 people, since we've got more than 12 days to do the same work in.
Let's start by figuring out the rate per person per day if 8 people do a quilt in 12 days. I'm going to adapt the standard distance formula, adding people:
d = r * people * time
1 quilt = r (8 people) (12 days)
1/96 quilt/person/day = r
Now use the same formula and our nice new quilt/person/day rate, remembering again that it's one quilt.
1 quilt = 1/96 quilt/person/day * p * 16 days
1 quilt = 16/96 quilt/person (p)
1 quilt = 1/6 quilt/person (p)
1 quilt (6 people/quilt) = p
6 people = p
Does this help?
Anyone have any tips on proportion problems?
Such as a question like this one:
If N dozen apples cost D dollars, what is the cost, in cents, of R apples at the same rate?
Here, PraxisMania, is why your math teacher always told you to label units: if you label units, you can see when they don't line up properly or when there need to be conversions.
n dozen apples = r (single) apples
d dollars = = = = c cents
The terms I've boldfaced are terms that don't correspond properly to each other: dollars don't correspond directly to cents, and dozens of apples don't correspond directly to single apples. Since we're supposed to end up with single apples and cents, it probably makes the most sense to convert dozens to singles and dollars to cents:
n(12) apples = r apples
d(100) cents = c cents
and then proceed from there.
Anyone have any tips on percent word problems??
Such as: A manufacturer finds that, on average, 0.2% of his items must be rejected. If, in a certain month, 5 items are rejected, how many items pass the inspection??
I started with multiplying 5 by 0.002 which is obviously not the right answer.
Anyone know how I can approach this questions and questions like it?
Thanks!! I knew it had to be converted I just didn't know the correct way to convert it. Thanks for the help!
You can use proportions to solve percent problems: the trick is that one fraction ALWAYS has a denominator of 100 and a numerator that's the percent. And in the other fraction, the "of" number - the one that corresponds to 100% - is in the denominator, always:
"is" = percent
"of" = 100
In the problem you've given, 0.2% is the percent (duh!); we plant it in the numerator of the percent fraction. And 5 is the number of items that fail, out of a number we don't know that's the total number of items produced - that total number of items produced is the "of" number that corresponds to 100%, so that number goes in the denominator:
"is" = 5 = 0.2
"of" = t = 100
You can cross-multiply to solve: 500 = 0.2t and so on. Or you can simply divide 5 by the decimal equivalent of 0.2%, which would be 5/0.002 = 2500.
That's how I did it as well. However, the answer key says 2495?
Hm. Where'd you get the problem?
Sep 6, 2007
I got the problem out of a algebra book I got from the library.
Do you have any tips on age problems?
I can't seem to get them understood in my head.
Any time they say "years ago", you're going to subtract from the current age.
Any time they say "Years from now", you're going to add to the current age.
And very often a chart will help:
John's age: now-- 5 years ago etc.
Mary's age: now-- 5 years ago etc.
That's probably sloppy proofreading, then; the question may have been changed from a version in which there were 2495 products and you were to figure out how many of them 0.2% would be.
My recollection is that Praxis I math questions are all multiple choice. That being the case, the prudent test taker goes with the closest answer that makes sense. Now if we calculate 0.2% of 2495, the result of the calculation is 4.99. But 5 is the sensible answer, because most factories cannot produce 99/100 of a product - and the wise factory owner will round UP to the nearest whole unit when budgeting for this sort of thing, not DOWN.
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