Search found 8 matches
An old post but I have a straightforward solution: P(Andrew is selected AND Karen not selected) = [1 - P(Andrew not selected in one of the 4 selections)] * P(Karen not selected in the subsequent 3 selections) = [1 - (7/8 * 6/7 * 5/6 * 4/5)] * (6/7 * 5/6 * 4/5) = [1 - 4/8] * 4/7 = 1/2 * 4/7 = [spoile...
- by osama_salah
Fri Jul 08, 2016 10:15 pm- Forum: Problem Solving
- Topic: 8 Volunteers for Charity Event
- Replies: 4
- Views: 9224
Why did we assume that a letter can not be repeated? e.g. out of B,C,D,F,G,H,J and A,E,I,O we can get: BACAD and ECCEF Out of 7 consonants and 4 vowels, how many words of 3 consonants and 2 vowels can be formed? A. 210 B. 1050 C. 25200 D. 21400 E. None of these Take the task of creating 5-letter wor...
- by osama_salah
Mon Jul 04, 2016 7:56 am- Forum: Problem Solving
- Topic: how many words
- Replies: 6
- Views: 4684
As every choice has an OR , both conditions must be true. Let's check: a)x=-1 OR y=0: x=-1: 0*y = y --> false, as y may be any value (e.g. 5) This also excludes choice d) b)x=0 OR y=0: x=0: 1*y = y --> true, let's proceed to the second condition y=0: 0*(1+x)=0 --> true, regardless x's value So, the ...
- by osama_salah
Fri Jul 01, 2016 7:59 am- Forum: Problem Solving
- Topic: If (1+x)y=y, which of the following must be true?
- Replies: 3
- Views: 1670
avgerage_speed = total_distance / total_time
5v/4 = (v.t + 2v.t1) / (t+t1)
divide both sides by v:
5/4 = (t + 2.t1) / (t+t1)
Thus:
5.t + 5.t1 = 4.t + 8.t1
Then:
3.t1 = t --> t1=[spoiler]t/3[/spoiler]
So, the correct answer is [spoiler](2)[/spoiler]
- by osama_salah
Fri Jul 01, 2016 7:46 am- Forum: Problem Solving
- Topic: Average
- Replies: 2
- Views: 1303
- by osama_salah
Tue Jun 28, 2016 4:49 am- Forum: GMAT Math
- Topic: General GMAT Query
- Replies: 9
- Views: 5541
How did you calculate 280² - 200² = 38,400 ? A small, rectangular park has a perimeter of 560 feet and a diagonal measurement of 200 feet. What is its area, in square feet? A) 19200 B) 19600 C) 20000 D) 20400 E) 20800. Let L and W equal the length and width of the rectangle respectively. perimeter...
- by osama_salah
Mon Jun 27, 2016 5:29 am- Forum: Problem Solving
- Topic: area
- Replies: 11
- Views: 5122
Amr, You assumed that the frequency increases linearly but is not true. It increases exponentially. That is, your solution assumes that the difference between any frequency and the next one is constant whereas the question mentions that the ratio between a frequency and the next one is constant. So,...
- by osama_salah
Wed Jun 15, 2016 8:32 am- Forum: Problem Solving
- Topic: Word problem
- Replies: 7
- Views: 6701
Sorry for this out-of-date reply but I have an irritating question: How long is solving this question supposed to take? 
- by osama_salah
Wed Jun 15, 2016 2:08 am- Forum: Problem Solving
- Topic: Advanced Quant Manhattan Question
- Replies: 11
- Views: 7034