Search found 24 matches
Five DS questions for practice today. Try !
No.1 The probability for A to happen is 40%, for B to happen is 65%. The probability for any one of them to happen? （1）A and B are independent （2）The probability for A and B both not to happen is 22% For this question, we can tell from choice 2 that the probability for A and B both to happe...
- by neilcao
Mon Jan 24, 2011 8:09 am- Forum: Data Sufficiency
- Topic: Five DS questions for practice today. Try !
- Replies: 8
- Views: 1562
Is the answer supposed to be 48? 12 students, assume if each choses only one song. 12 songs= 12 students. Even if only 2 songs are chosen, if should not affect the total number of 12 students.
Therefore, 4 x 12 = 48
Maybe wrong. I am nor sure.
- by neilcao
Tue Dec 14, 2010 5:32 pm- Forum: Problem Solving
- Topic: PS 4
- Replies: 3
- Views: 1007
GHong14 wrote:Can anyone explain why the selected answer is wrong
Do you mean option A is wrong? I tried but I also got the answer A, which is 0.30$
600/10^6 = 0.0006
0.0006 x 500 = 0.30
Anyone has any idea about this???
- by neilcao
Tue Dec 14, 2010 5:15 pm- Forum: Problem Solving
- Topic: PS 2
- Replies: 1
- Views: 744
Sorry worked it out, saw it wrong. Sorry how did you get this ,can u break it a bit further please? => 5^x[1 - 1/125] = 124*5^y => [5^x * 124]/125 = 124*5^y 5^x[1 - 1/125] became [5^x * 124]/125 Thanks Just to clarify for others Q should be 5^x - 5^[x-3] = 124 * 5^y => 5^x - [5^x/5^3] = 124*5^y => 5...
- by neilcao
Wed Dec 08, 2010 8:09 am- Forum: Problem Solving
- Topic: y in terms of x
- Replies: 7
- Views: 20115
Sorry how did you get this ,can u break it a bit further please? => 5^x[1 - 1/125] = 124*5^y => [5^x * 124]/125 = 124*5^y 5^x[1 - 1/125] became [5^x * 124]/125 Thanks Just to clarify for others Q should be 5^x - 5^[x-3] = 124 * 5^y => 5^x - [5^x/5^3] = 124*5^y => 5^x[1 - 1/125] = 124*5^y => [5^x * 1...
- by neilcao
Wed Dec 08, 2010 8:06 am- Forum: Problem Solving
- Topic: y in terms of x
- Replies: 7
- Views: 20115
Sorry this way do you mean each individual will be sufficient, then it is not C? Answer should be (C). 1. If a number is factor of square of other number then same number will also be factor of other number. In simple words, if A is factor of square of B then A is also factor of B. ex. B = 60 square...
- by neilcao
Mon Dec 06, 2010 3:17 am- Forum: Data Sufficiency
- Topic: Factors
- Replies: 8
- Views: 1270
Hi, Undertand the overall logic now. But not sure how you generated the following: For example let x = 2 then (x-1) (x+1) = 2 thus r = 2 For example let x = 4 then (x-1) (x+1) = 15 thus r = 15 Why is the remainder r =2 and 15 in these two situations? Can you please break it down into more detailed p...
- by neilcao
Sun Dec 05, 2010 11:49 pm- Forum: Data Sufficiency
- Topic: Remainder with division by 24
- Replies: 7
- Views: 1461
Sorry, don't know how to work out the last step: 2^20 - 2^19 = 2^19(2-1)
Why is that? May be a silly questions to ask.
- by neilcao
Sat Dec 04, 2010 10:13 pm- Forum: Problem Solving
- Topic: then x20 – x19 =
- Replies: 4
- Views: 1621
Sequence problems. How to solve this?
If the sequence X1, X2,X3,...., Xn .......is such that X1=3 and Xn+1 = 2Xn- 1 for n=1, then X20-X19=??
Any body knows how to approach this kind of problem?
Thanks
- by neilcao
Sat Dec 04, 2010 9:10 pm- Forum: Problem Solving
- Topic: Sequence problems. How to solve this?
- Replies: 1
- Views: 1290