vwjetty wrote:
Well here's a few. Took me right at or over 2 min to do. And still didn't get some of them right.
A student took 7 tests. The student's average score on the first 5 tests was 73. The student's average score on the final 5 of these 7 tests was 79. How much greater than the student's average score on the first 2 of these tests was the student's average score on the final 2 of these tests?
6
7
10
15
18
The first 5 tests had an average score 6 lower than the last 5 tests. since avg = total of terms/# of terms, and there were five terms (the tests) in each case, we can deduce that the total score of the second set of tests was 30 points higher than that of the first.
However, note that the two sets of tests overlap in the middle! Both are counting the middle three. That means those 30 extra points must come
entirely from the difference between the first two and the last two. Since we have 30 extra points split among two tests, we can then deduce that the last two tests must have averaged 15 points higher than the first two.
Quote:
Each supervisor in the company oversees 18 workers. After a reorganization, the number of workers overseen by each supervisor will be 26. The number of workers remained the same after the reorganization. How many supervisors will be needed to oversee the company ’ s workers after such a reorganization?
(1) The company currently has 13 supervisors.
(2) Four fewer supervisors will be needed after the reorganization.
The statement gives us three variables--the original number of supervisors (S), the number of workers (W), and the new total of supervisors post-reorg. (N). It also gives us two equations: since a supervisor oversees 18 workers, there are 18 times as many workers orginally, so 18S = W. Then, we lose some supervisors; afterwards, the equation is 26N = W.
Since we have three variables, the mathematical properties of systems of equations tell us that we can always solve three unique equations using some or all of those variables. Since the stem gives us two equations, it means a unique equation--
any unique equation!--will be sufficient unless it introduces another variable
or is non-linear--any variables to powers higher than 1, or any two variables multiplied by one another.
1) S = 13 is a unique equation. Sufficient.
2) S - 4 = N is a unique equation. Sufficient.
The correct answer is (D), Either choice is sufficient.
Quote:
John is j years old and Keith is k years old, and both are at least one year old. Is j > k ?
(1) jk = 2 j
(2) j + k = 2 j
1) divide both sides by j. K = 2. J = ?
J could be 1, or J could be 3; he could be older or younger. Insufficient.
2) Subtract J from both sides. K = J. If k is equal to j, is is NOT less than J; the answer to this question is defnitely no. Sufficient.
The correct answer is (B), 2 alone is sufficient.
So as you can see, just like th GMAT,
Kaplan questions are often designed to lure people in with the temptation of unnecessary algebra. But don't worry! As you go through the
Kaplan course, you'll get a great sense of what common tricks and patterns you can use to avoid these pitfalls.
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