请教OG 数学 PS第217题

joyjojo821 · 发表于 2010-3-12 10:52:31

217. In a certain game, a large container is filled with red,
yellow, green, and blue beads worth, respectively, 7,
5, 3, and 2 points each. A number of beads are then
removed from the container. If the product of the point
values of the removed beads is 147,000, how many
red beads were removed?
(A) 5
(B) 4
(C) 3
(D) 2
(E) 0
Arithmetic Properties of numbers
From this, the red beads represent factors of 7 in
the total point value of 147,000. Since 147,000 =
147(1,000), and 1,000 = 10 3, then 147 is all that
needs to be factored to determine the factors of 7.
Factoring 147 yields 147 = (3)(49) = (3)(72). Th is
means there are 2 factors of 7, or 2 red beads.
Th e correct answer is D.
看了解释还是不明白，有没有人解释一下？

chriscatty · 发表于 2010-3-12 11:45:25

首先题目中的product是乘积的意思，也就是说147000代表的是4种球的points的乘积。
147000=147×1000，1000=10×3也就是说有2×5×3，剩下的就是看147是怎么来的了
147=3×49＝3×7×7，也就是说肯定要有两个7才可以，那就是2个红球了

joyjojo821 · 发表于 2010-3-12 12:31:46

1000=10×3？？还是不明白。

joyjojo821 · 发表于 2010-3-12 12:33:55

看明白了，谢谢楼上的解释！

请教OG 数学 PS第217题

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