A box contains 100 balls, numbered from 1 to 100. If three balls are selected at random and with replacement from the box, what is the probability that the sum of the three numbers on the balls selected from the box will be odd?
来源： 2635人已做 700难度 55.9%正确率
The 15 homes in a new development are each to be sold for one of three different prices so that the developer receives an average (arithmetic mean) of $200,000 per home. If 4 of the homes are to be sold for $170,000 each and 5 are to be sold for $200,000 each, what will be the selling price of each of the remaining 6 homes?
来源： 680人已做 600难度 94.3%正确率
来源：破解版07 380人已做 600难度 91.8%正确率
A certain class, consisting of a lecture and a question-and-answer session, lasted from 2:45 to 4:30 one afternoon. If the lecture lasted from 2:45 to 4:15, then the question-and-answer session was what fraction of the total class time?
来源： 868人已做 600难度 90.2%正确率
The table shows the number of residents in a certain development who are willing to contribute to build a swimming pool, provided the required contribution does not exceed the amount indicated by the resident. The following three amounts are being considered as the required contribution. Which would ensure that more than half of the residents contribute to build the pool?Ⅰ.$33 Ⅱ.$48Ⅲ.$55
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If S=[n(n+1)] /2 and n = 40, then S =
来源： 652人已做 600难度 92.5%正确率
In a survey of 248 people, 156 are married, 70 are self-employed, and 25 percent of those who are married are self-employed. If a person is to be randomly selected from those surveyed, what is the probability that the person selected will be self-employed but not married?
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A circular cloth with a diameter of 20 inches is placed on a circular tray with a diameter of 24 inches. What fraction of the tray's surface is not covered by the cloth?
来源： 567人已做 600难度 89.6%正确率
If x and y are positive, which of the following must be greater than 1/√（x+y） ?
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Square S is inscribed in circle T. If the perimeter of S is 24, what is the circumference of T ?
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The contingency-fee system, which allows lawyers and their clients to agree that the lawyer will be paid only in the event of success, does not increase the number of medical malpractice lawsuits brought against doctors. As attorneys must cover the costs for their time and research,they want to be assured that any medical malpractice case they accept on a contingency-fee basis has substantial merit. Consequently, attorneys turn away many people who come to see them, for lack of a good case. The argument above is most vulnerable to criticism on the grounds that it fails to
【OG20-P811-889题】While many of the dinosaur fossils found recently in northeast China seem to provide evidence of the kinship between dinosaurs and birds, the wealth of enigmatic fossils seem more likely at this stage that they will inflame debates over the origin of birds rather than settle them.
【OG20-P276-272题】Lines k and m are parallel to each other. Is the slope of line k positive?(1) Line k passes through the point (3,2).(2) Line m passes through the point (−3,2).
【OG20-P602-740题】Studies in restaurants show that the tips left by customers who pay their bill in cash tend to be larger when the bill is presented on a tray that bears a credit card logo. Consumer psychologists hypothesize that simply seeing a credit-card logo makes many credit card holders willing to spend more because it reminds them that their spending power exceeds the cash they have immediately available.Which of the following, if true, most strongly supports the psychologists' interpretation of the studies?
Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.
Surveys have shown that in up to 40 percent of elderly people living independently in affluent countries, the consumption of one or more essential nutrients is insufficient or they have deficient levels of these nutrients in their blood.
It is true of both men and women that those who marry as young adults live longer than those who never marry. This does not show that marriage causes people to live longer, since, as compared with other people of the same age, young adults who are about to get married have fewer of the unhealthy habits that can cause a person to have a shorter life, most notably smoking and immoderate drinking of alcohol. Which of the following, if true, most strengthens the argument above?
Recently implemented “shift-work equations” based on studies of the human sleep cycle have reduced sickness, sleeping on the job, fatigue among shift workers, and have raised production efficiency in various industries.
Originally developed for detecting air pollutants, a technique called proton-induced X-ray emission, which can quickly analyze the chemical elements in almost any substance without destroying it, is finding uses in medicine, archaeology, and criminology.
A photographer will arrange 6 people of 6 different heights for photograph by placing them in two rows of three so that each person in the first row is standing in front of someone in the second row. The heights of the people within each row must increase from left to right, and each person in the second row must be taller than the person standing in front of him or her. How many such arrangements of the 6 people are possible?