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Math help center
Arachnotron
1658 replies103 threads Senior Member
Give me any SAT Reasoning Test math question (or a question from a simulated practice test) and I'll post a solution. Specify detail (just the math work or explicit reasoning or w/e) if you want. I'll post ridiculously detailed solutions by default.
312 repliesPost edited by Arachnotron on
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Replies to: Math help center
#5 pg. 472 of Blue Book
#6 pg. 472 of BB
#8 pg. 473 of BB
1. http://img16.imageshack.us/img16/3329/q34g.jpg
2. http://img193.imageshack.us/img193/9058/78224058.jpg
3. http://img195.imageshack.us/img195/6129/52012792.jpg
Thanks.
Image 1:
#15:
Since OD bisects <AOF, you know that m<AOD = m<DOF, and since you know that OC bisects <AOE, that m<AOB + m<BOC = m<COD + m<DOE, and since OB bisects <AOD, you know that m<BOC + m<COD = x = 40
Now since m<BOC + m<COD = 40, and since we know that OD bisects <AOF, we know that
40 + m<BOC + m<COD = 30 + m<DOE. Substituting, it is easy to see that the expression boils down to 40 + 40 = 30 + m<DOE, which gives that m<DOE is 50.
Finally, we want to find <BOE, which we can do by adding m<BOC + m<COD + m<DOE, which from the information we have derived simplifies to 40 + 50 = 90
#17:
Since we remove every 4 inches, it is useful to find out how many triangles we will remove. This can be found by: 80/4 = 20. Then, notice that for every 1 inch you remove, you gain back 2 inches. So we gain back 20(2-1) = 20 inches, which would make our total length 100 .
#20
You know that the total rope length will be y + 4x, so the insight needed is an expression of y in terms of x. Luckily, we have area which gives xy = 4000. Now, rearranging, we see that x = 4000/y, which we can substitute into our expression to yield 16000/y, choice B
#7
Sum of the arc measures is 2pi or 360 degrees. It's divided into 5 equal segments. ABC gets two of these segments, which leaves 3 of these segments to AEC. Thus ratio of ABC to AEC is 2:3, choice B .
Tom's rate: 100 ft/27 sec
Bill's rate: 90 ft/27 sec.
(27sec/90ft)(100ft) = 30 seconds.
filling entries of an initially empty 2008
The answer is Barbara.
Take a look at it this way: whenever Alan puts some number, n, in an entry in some row, Barbara can just write its negative in the same row. If you continue this process -- since there are an even number of spots -- all the rows will add up to zero so you end up with a matrix that is rank deficient, thus proving Barbara has a winning strategy.
If four men need $24 worth of food for a three-day camping trip, how much will two men need for a two-week trip?
I got $56
If it takes 16 faucets 10 hours to fill 8 tubs, how long will it take 12 faucets to fill 9 tubs?
I got 15 hours
Are these solutions correct?
#1:
Correct.
#2:
16 faucets 10 hours to fill 8 tubs can be reduced to 2 faucets 10 hours hours to fill 1 tub
So, it would take 10/6 hours for 12 faucets to fill 1 tub, and then (5/3)(9) to fill 9 tubs, which gives you the correct answer of 15.