GMAT Prep(08) 输血一题求解

gmat2000

Tanya prepared 4 different letters to be sent to 4 different addresses.  For each letter, she prepared an envelope with its correct address.  If the 4 letters are to be put into the 4 envelopes at random, what is the probability that only 1 letter will be put into the envelope with its correct address?

概率很难。

nightingale

1/3

sdcar2010

This is akin to do the following:
1) put one letter into its corresponding evelope.
2) put the othe three letters into evelopes. Total possibilites are 6:
1  2  3
A  B  C
A  C  B
B  A  C
B  C  A
C  A  B
C  B  A
3) caculate what is the probability that all the othe three letters are in wrong evelopes.
Only C A B; B C A fulfil this requirement assuming A, B, C matches with 1, 2,3, respectively.

2/6 = 1/3

sissi8466

这道数学题的“in the box” 什么意思啊， 在哪看啊

helenlife

gmat2000

see Floor10 on pg1

gmat2000

Before being simplified, the instructions for computing income tax in Country R were to add 2 percent of one's annual income to the average (arithmetic mean) of 100 units of Country R's currency and 1 percent of one's annual income.  Which of the following represents the simplified formula for computing the income tax, in Country R's currency, for a person in that country whose annual income is I ?

why 50+I/40?

gmat2000

List K consists of 12 consecutive integers.  If -4 is the least integer in list K, what is the range of the positive integers in list K ?

(A)  5
(B)  6
(C)  7
(D) 11
(E) 12
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【答案】B
【思路】-4 -3 -2 -1 0 1 2 3 4 5 6 7 正整數的範圍 ˙7-1=6

But should the range be 7, if count one by one from 1 to 7?

段小q

真的是老奸巨猾啊！！！