November 20th, 2009 | 
Author: One-fifth of the light switches produced by a cer¬tain factory are defective. Four-fifths of the defective switches are rejected and 1/20 of the nondefective switches are rejected by mistake. If all the switches not rejected are sold, what percent of the switches sold by the factory are defective?
(A) 4%
(B) 5%
(C) 6.25%
(D) 11%
(E) 16%
Highlight to see answer: B
Please post your explanations in the comments below!
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The figure above represents a rectangular parking lot that is 30 meters by 40 meters and an attached semicircular driveway that has an outer radius of 20 meters and an inner radius of 10 meters. If the shaded region is not included, what is the area, in square meters, of the lot and driveway?
(A) 1,350Ï€
(B) 1,200 + 400Ï€
(C) 1,200 + 300Ï€
(D) 1,200 + 200Ï€
(E) 1,200 + 150Ï€
Highlight to see answer: E
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A student responded to all of the 22 questions on a test and received a score of 63.5. If the scores were derived by adding 3.5 points for each correct answer and deducting 1 point for each incorrect answer, how many questions did the student answer incorrectly?
(A) 3
(B) 4
(C) 15
(D) 18
(E) 20
Highlight to see answer: A
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Solution Y is 30 percent liquid X and 70 percent water. If 2 kilograms of water evaporate from 8 kilograms of solution Y and 2 kilograms of solution Y are added to the remaining 6 kilograms of liquid, what percent of this new solution is liquid X?
(A) 30%
(B) 30.3%
(C) 37.5%
(D) 40%
(E) 50%
x – y = 3
2x = 2y +6
The system of equations above has how many
solutions?
(A) None
(B) Exactly one
(C) Exactly two
(D) Exactly three
(E) Infinitely many
