Search found 80 matches
For the first question, you dont really need to calculate anything: (10^8 - 10^2)/(10^7 - 10^3) Relative to 10^8, 10^2 is very tiny. Think 100,000,000 - 100 = 99,999,900. Not that different from 10^8. Relative to 10^7, 10^3 is very tiny. So, in essence, you may think of (10^8 - 10^2)/(10^7 - 10^3) a...
- by grockit_jake
Mon Dec 14, 2009 10:00 am- Forum: Problem Solving
- Topic: Some difficult ones .
- Replies: 10
- Views: 2329
Personally, I find formulas to be an easy trap for test takers. There are a lot floating out there, and while you need the essential ones, many times you end up memorize a lot of stuff you may not need and it gets muddled in the anxiety of the real test. By no means am I discouraging the use of form...
- by grockit_jake
Mon Dec 07, 2009 1:48 pm- Forum: GMAT Math
- Topic: sum of all even numbers from 99 to 301
- Replies: 19
- Views: 80375
I like to convert to my final units first, but there is no "better" way:
1/2 s = 1/120 minute = 1/7200 hour
20 ft = 20/5280 miles = 1/264 miles
Miles/ hour = 7200/264 = 27.27 mph
- by grockit_jake
Fri Nov 20, 2009 12:37 pm- Forum: Problem Solving
- Topic: GMAT 700+ PS
- Replies: 4
- Views: 2430
You can do venn diagram or L matrix for these. I prefer L visually since you can add the totals vertically and horizontally without crossing your eyes.
Also remember that when you have 2 groups with an overlap,
Total = (All in A) + (All in B) - 2*(both)
- by grockit_jake
Thu Nov 19, 2009 4:52 pm- Forum: Data Sufficiency
- Topic: Overlooking the obvious
- Replies: 2
- Views: 1369
10 cups total
3 drank in 6th mile
2 cups leaked in 2 hours
1 left in canteen
4 remaining cups that were drank in first 5 miles
4 cups in 5 miles = 4/5 cups/mile
- by grockit_jake
Thu Nov 19, 2009 4:49 pm- Forum: Problem Solving
- Topic: Real GMAT question
- Replies: 2
- Views: 4776
Right you need both to solve. Instead of solving for the 2 possible values of n for each and then comparing, you can solve both equations in terms of n^2, set equal and solve for n that way.
- by grockit_jake
Thu Nov 19, 2009 4:46 pm- Forum: Data Sufficiency
- Topic: DS on equations
- Replies: 5
- Views: 1714
The simple average formula can be expressed: Avg = SUM/# , or as SUM = Avg*# The stimulus tells us that SUM(t) = SUM(s), therefore we know the products of their respective Avgs and #s must be equal (1) Avg(s) < Avg(t), therefore #(t) >#(s) to make Avg*# = Avg*#. Sufficient. (2) The stimulus does not...
- by grockit_jake
Thu Nov 19, 2009 4:17 pm- Forum: Data Sufficiency
- Topic: Average + Median
- Replies: 12
- Views: 2686
There's a typo on D in the original question that carlcat posted.
it should read.
D. d = (p - 0.18)/1.04
- by grockit_jake
Tue Nov 17, 2009 3:49 pm- Forum: Problem Solving
- Topic: Word Problem
- Replies: 9
- Views: 1579
Close enough doesn't count. Sorry. The reason it's so close is that 0.18 is really small relative to $5 or $3. You have to "undo" the equation you put forward. If you set d, then multiply by 1.04 and then subtract, to "undo" you must add first, then divide the sum. Try answer C w...
- by grockit_jake
Tue Nov 17, 2009 3:27 pm- Forum: Problem Solving
- Topic: Word Problem
- Replies: 9
- Views: 1579
If you have n consecutive odd/even numbers, and n is ODD, then both the mean and median = the (n+1)/2 -th term.
If you have n consecutive odd/even numbers, and n is EVEN, then mean and median = nth term + 1
Same rules apply for all arithmetic progressions.
- by grockit_jake
Tue Nov 17, 2009 10:53 am- Forum: GMAT Math
- Topic: mean=median
- Replies: 3
- Views: 2376
I think the easiest way here is to use artificial numbers, because whatever you pick, the fraction will be the same. Make sure you pick numbers that are multiples of the fractions provided in the question. Instead of using variables that get hard, just pick easy numbers. I picked: Gold Limit: 15 Pla...
- by grockit_jake
Tue Nov 17, 2009 10:47 am- Forum: Data Sufficiency
- Topic: Credit
- Replies: 2
- Views: 1335
The easiest way to start is to set up the equation in terms of d and p in the way the stimulus presents the question:
p = 1.04d + 0.18
Now solve for d:
p - 0.18 = 1.04d
d = (p - 0.18) / d
- by grockit_jake
Tue Nov 17, 2009 10:41 am- Forum: Problem Solving
- Topic: Word Problem
- Replies: 9
- Views: 1579
I agree -- it helps here to just pick arbitrary (small and relevant) numbers that work with the fractions given: Total radios should equal a multiple of 3: 2 basic 1 deluxe Hrs to produce deluxe is 7/5 hrs to produce basic, so: Time for basic = 5 hrs Time for deluxe = 7 hrs Total time for basics = 2...
- by grockit_jake
Fri Nov 13, 2009 2:45 pm- Forum: Problem Solving
- Topic: Ratio of Radio production
- Replies: 2
- Views: 1400
With exponents, remember that you flip the fraction in the base to eliminate the negative in the exponent. I think the best strategy would be to quickly eliminate all the negatives from the exponents by flipping the fractions. This will make it visually easier. 2 other things to remember are that wh...
- by grockit_jake
Fri Nov 13, 2009 2:39 pm- Forum: Problem Solving
- Topic: positives and negatives
- Replies: 1
- Views: 1401
yes, no need to plug in and solve on data sufficiency questions.
If there are 2 linear eqs and 2 unknowns (that are not identical multiples of each other) then you have a unique solution.
- by grockit_jake
Fri Nov 13, 2009 2:30 pm- Forum: Data Sufficiency
- Topic: Age?
- Replies: 6
- Views: 2788