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During a trip, Francine traveled x percent of the total distance at an average speed of 40 miles per hour and the rest of the distance at an average speed of 60 miles per hour. In terms of x, what was Francine’s average speed for the entire trip?
A.180-x/2 B.X+60/4 C.300-x/5 D.600/115-X E.12,000/x+200
Key is E. why?
If x2 + 3x + c = (x + a)(x + b) for all x, what is the value of c ? (1) a = 1 (2) b = 2 A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statements (1) and (2) TOGETHER are NOT sufficient.
Key is D. why? | 
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发表于 2008-2-9 11:13:00
