A couple of Maths Qs for As ?
| 1. By the use of a certain code to distinguish 12 participants, this code can be one letter or two letters in alphabetical order. How many at least the numbers of the letters should be used?
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Is the answer 5? A B C D E 4 letters: 3+2+1+4=10
AB BC CD DE 5 letters: 4+3+2+1+5= 15
AC BD CE
AD BE
AE
2. A gentleman possesses 5 suits and 7 ties, in which only one suit can match exactly the specific tie, and others can be matched in will ( randomly ). How many combinations does the man can match his tie and suit?
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C(4,1)* C(6,1) +1= 25 ???? Why the answer in Feifei’s handouts is 29? How to solve this out?
3. A parallelogram with the length of two sides 6 and 7, which one of the followings can be the area of the parallelogram?
A) 21 B) 42 C) 84
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How to figure out?
4. From 1-100 inclusive, what is the possibility of N*(N+1) that can be divided by 4? What is the possibility of N*(N+1) that can be divided by 3?
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I calculated by writing the first several numbers and found out that for 4 numbers, there are two that can be divided by 4 and 2 out of 3 that can be divided by 3. Therefore the answer should be ½ and 2/3.
Is that right? And is there any easy way to think out of the Q?
5. There are 8 books, 6 of them are paper books and 2 of them are hardcover books, what is the combination of at least one hardcover book?
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C(2,1) * C ( 6, 3)
Why C ( 6, 3) ? Took for 4 times? Not sure! Thx!
6. DS: 45% the apartments with <=3 people living in each one. What’s the median?
(1) 80% of the apartments have <=5
(2) 35% of the apartments have >=5
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Is the answer B? Why or Why not?
Tons of Thx!
[em18][em18] |
