求助：一些数学题

mary87 · 发表于 2009-11-10 12:33:43

也许在高手的眼中都比较简单，但还是希望大家多多帮忙，不盛感激！

1. If the sum of four consecutive positive integers a three digit multiple of 50, the mean of these integers must be one of X possible values, where X=

A. 7 B. 8 C. 9 D. 10 E. more than 10

2. E is a collection of four odd integers and the greatest difference between any two integers in E is 4. The standard deviation of E must be one of how many numbers?

A. 3 B. 4 C. 5 D. 6 E.7

3. Of the 60 animals on a certain farm, 2/3 are either pigs or cows. How many of the animals are cows?

(1) The farm has more than twice as many cows as it has pigs.

(2) The farm has more than 12 pigs.

4. The rate of a certain chemical reaction is directly proportional to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical b is increased by 100, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?

A. 100% decrease B. 50% decrease C. 40% decrease

D. 40% increase E. 50% increase

OG12-PS-98

On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?

A. 5 B. 50 C. 10⁵ D. 5¹⁰ E. 8^{10 -}3¹⁰

5. Running at their respective constant rates, machine X takes 2 days longer to produce w widgets than machine Y. At these rates, if the two machines together produce 5/4 w widgets in 3 days, how many days would it take machine X alone to produce 2w widgets?

A.4 B.6 C.8 D.10 E.12

6. The dimensions of a semicircular cross section of a one-way tunnel are 20 feet. The single traffic lane is 12 feet wide and is equidistant from the sides of the tunnel. If vehicles must clear the top of the tunnel by at least ½ foot when they are inside the traffic lane, what should be the limit on the height of vehicles that are allowed to use the tunnel?

A.5½ ft B.7½ ft C.8 ½ ft D.9½ ft E.10 ft

7. On a certain transatlantic crossing, 20 percent of a ship’s passengers held round-trip tickets and also took their cars abroad the ship. If 60 percent of the passengers with round-trip tickets did not take their cars abroad the ship, what percent of the ship’s passengers held round-trip tickets?

A.33 1/3% B.40% C.50% D.60% E.66 2/3%

求助：一些数学题

所属分类: GMAT考试

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