再说这个 In a certain year, the diff between Mary's and Jim's annual salaries was twice the diff between Mary's and Kate's annual salaries. If Mary's annual salary was the highest of 3 people, what was the average(arithmetic mean) annual salasy of 3 people that year? (1) Jim's annual salary was $30,000 that year (2) Kate's annual salary was $40,000 that year 先设Mary(M), Jim(J), Kate(K), Mary的最高,那上面的题干就可以转化成M-J=2(M-K),那就是M=2K-J=$50,000,三个人的平均值就是30000+40000+50000/3=40000
这题可以直接跟到起题干算: Malik's recipe for 4 servings of a certain dish requires 1.5 cups of pasta. According to this recipe, what is the number of cups of pasta that Malik will use the next time be prepare the dish? (1) the next time he prepare the dish, Malik will make half as many servings as he didi the last time he prepared the dish(这次只有上次的一半,那就是3杯) (2) Malik used 6 cups of pasta the last time he prepared the dish(上次是6杯,不管serving有多少,算不算都无所谓的)
If n is a multipal of 5 and n=p^2q, where p and q are prime numbers, which of following must be a mutipal of 25 1. P^2 2. q^2 3. pq 4. p^2q^2 5. p^3q 这个用排除法: 1.q有可能是5的倍数而p不是,所以这个不对 2.p有可能是5的倍数而q不是,所以这个也不对 3.p,q有可能只有一个是5的倍数,所以还是不对 4.无论是p还是q,总有一个必然是5的倍数,自然各自的平方总有一个是25个倍数 5.同1
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发表于 2010-10-28 18:14:05
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