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If the 3 points lie on the same line, they are collinear. For 3 points to be collinear, the slope of 2 points taken at a time will be equal. A(5,3), B(x,y), C(3,2) slope for 2 points(x1,y1) and (x2,y2) is given by (y2-y1)/(x2-x1) Slope m1 = (y-3)/(x-5) slope m2 = (2-y)/(3-x) m1 = m2 as they lie on t...

by gmatmath

Sat Apr 07, 2012 9:07 pm
Forum: Problem Solving
Topic: co-ordinate geometry.
Replies: 3
Views: 672

Yes, line 1 is parellel to the y axis because the equation of a line parallel to the y axis will have the equation x = k, where k is any constant.

In this case we have x = 4.

by gmatmath

Sat Apr 07, 2012 8:57 pm
Forum: Problem Solving
Topic: co-ordinate geometry.
Replies: 4
Views: 812

S1 = 5850 + [10% x (8250 + 40% x S1)] S1 = 5850 + [0.1 x (8250 + 0.4S1)] [I have converted 10% in decimals as 0.1 and 40% as 0.4] S1 = 5850 + [825 + 0.04S1] [multiplying 0.1 with (8250 + 0.4S1)] S1 = 5850 + 825 + 0.04S1 S1 - 0.04S1 = 6675 ==> 0.96S1 = 6675 ==> S1 = 6675/0.96 ==> S1 = 6953.125, when ...

by gmatmath

Fri Apr 06, 2012 10:03 pm
Forum: Problem Solving
Topic: Solve for S1
Replies: 4
Views: 1781

This problem can have 2 solutions depending on how the parenthesis are placed.

case1: [2^(4-1)]^2 / 2^(3-2)
= (2^3)^2 / 2
= 2^6/2
= 2^5

case2: 2^[(4-1)^2]/2^(3-2)
= 2^[3^2]/2
= 2^9/2
=2^8

by gmatmath

Fri Apr 06, 2012 8:41 am
Forum: Problem Solving
Topic: 2^(4-1)^2 / 2^(3-2)
Replies: 3
Views: 818

if (5,3), (x,4) and (3,2) lie on the same line, they are collinear. This means that the slope of any 2 points taken should be the same. 1)(5,3) and (x,4) slope = (4-3)/(x-5) 2) (5,3) and (3,2) slope = (2-3)/(3-5) Now, equating both the slopes 1/(x-5) = -1/-2 ==> 1/(x-5) = 1/2 since the numerators ar...

by gmatmath

Fri Apr 06, 2012 8:34 am
Forum: Problem Solving
Topic: co-ordinate geometry .
Replies: 3
Views: 633

We can solve this problem by trial and error method. We will plug in values for n from 1,2,3,.... and chk for which value of n, 2^n = n^2. 1)n=1 2 = 1 FALSE 2)n=2 2^2 = 4; n^2 = 4 TRUE 3) n =3 2^3 = 8; 3^2 = 9 FALSE 4) n=4 2^4 = 16; 4^2=16 TRUE 5)n=5 2^5=32; 5^2=25 FALSE 6) n=6 2^6=64; 6^2 =36 FALSE...

by gmatmath

Fri Apr 06, 2012 8:12 am
Forum: Problem Solving
Topic: Integer N
Replies: 5
Views: 743

we will find the equation of the line passing through (-10, -18) and (20, 22). The slope = (22-(-18))/(20-(-10))= 40/30 so, slope = 4/3 the line's equation is: y-(-18) = (4/3)*(x-(-10)) y +18 = (4/3)*(x+10) this line passes through (x, 2). Hence we will plug in y = 2 and find x. 2+18=(4/3)*(x+10) 20...

by gmatmath

Fri Apr 06, 2012 8:04 am
Forum: Problem Solving
Topic: co-ordinate geometry .
Replies: 5
Views: 798
by gmatmath

Fri Apr 06, 2012 7:45 am
Forum: Problem Solving
Topic: GMAT Prep #2_PS Triangles and Squares #12
Replies: 2
Views: 626

In this question, we will be deriving teh answer from the choices. a) f(x) = 1-x ==> f(1-x) = 1-(1-x)= x hence f(x) not= f(1-x) b)f(x) = 1-x^2 f(1-x) = 1-(1-x)^2 = 1-(1+(x^2)-2x) = (-x^2)+2x here, f(x) not=f(1-x) c) f(x) = (x^2)-(1-x)^2 f(1-x)=(1-x)^2-(1-(1-x))^2 = (1-x)^2 -(x^2) f(x) not = f(1-x), ...

by gmatmath

Fri Apr 06, 2012 7:09 am
Forum: Problem Solving
Topic: function f(x)
Replies: 4
Views: 882

to find x, the sum upto n terms is Sn, we need to make use of AP. the first term 'a' = 40, last term Tn = 60, common difference'd' = 2 hence, number of terms 'n' = ? Pluging in the formula Tn = a + (n - 1)d, we get, 60 = 40 + 2(n - 1) ==> 20 = 2(n - 1) ==> n - 1 = 10 ==> n = 11 there are 11 terms be...

by gmatmath

Fri Apr 06, 2012 1:56 am
Forum: Problem Solving
Topic: GMAT Test 2_PS Number Prop #3
Replies: 4
Views: 698

Let us assume the side of the square to be 'a' cm. So, its area A = a^2 sq.cm Perimeter P = 4a. Given A = 2P + 9 We will now plug in the values of A and P in the above equation. We get, a^2 = 2(4a) + 9 a^2 = 8a + 9 ==> a^2 - 8a - 9 = 0 ==> a^2 - 9a + a - 9 = 0 [factors 0f 9 such that difference is 8...

by gmatmath

Fri Apr 06, 2012 1:47 am
Forum: Problem Solving
Topic: GMAT Test 2_PS Square #15
Replies: 2
Views: 637

Given the ratio of length to width to height = 3:2:2.
so, Let the length'l' = 3k, width'w' = 2k and height'h' = 2k
Volume = lxwxh
x = 3k*2k*2k
x = 12k^3
==> k = (x/12)^(1/3)
so, height 'h' = 2k = 2[(x/12)^(1/3)
or h = two times the cuberoot of (x/12)

by gmatmath

Fri Apr 06, 2012 1:39 am
Forum: Problem Solving
Topic: Rectangular problem .
Replies: 2
Views: 725

initially there are 70 students. This can be arranged in 2 ways: 1) 10 students of 7 rows each or 2) 7 students of 10 rows each. If we take choice 1 , adding 4 more rows,makes it 11 rows and reduce 2 students from each row ,we get 8 students in each row. Since there are only 70 students, we will hav...

by gmatmath

Fri Apr 06, 2012 1:20 am
Forum: Problem Solving
Topic: students are made to stand
Replies: 7
Views: 1097

Please post your questions in quant and I will help you solve them with clear explanations.

by gmatmath

Thu Apr 05, 2012 7:29 pm
Forum: GMAT Math
Topic: One month until 3rd attempt. Need Quant study suggestions
Replies: 2
Views: 1881

First, we have to find 'n'. Let us find 'n' by trial and error method. 1) n = 11, so, n%5 = 1,n%7 = 4 [% means gives the remainder] 2) n = 16 so, n%5 = 1, n%7 = 2 3)n = 21 so, n%5 = 1, n%7 = 0 4)n = 26 so, n%5 = 1, n%7 = 5 5)n = 31 so, n%5 = 1, n%7 = 3 Hence, we will consider the 5th option as it sa...

by gmatmath

Thu Apr 05, 2012 7:20 pm
Forum: Problem Solving
Topic: Basic strategy - number properties
Replies: 6
Views: 737