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good posts. You can also do this problem by odds and evens. If n is even, then the product is sure to be divisible by 8 (or three 2's) n is even so it is divisible by one 2. (n+2) is divisible by 4 since it has two 2's. 1/2 of all numbers are even. If n is odd, (n+1) should be divisible by 8 for the...

by ssmiles08

Wed Oct 28, 2009 4:31 am
Forum: Problem Solving
Topic: n(n+1)(n+2) divisibility by 8
Replies: 9
Views: 8225

Firstly, you are choosing two shoes out of 20. and 2 of them have be from the same pair.

2C2/20C2 = 1/190

next, you have 10 different pairs. So there are 10 more possible ways you can get a pair of shoes.

so it is 1/190 * 10 = 1/19 (C)

by ssmiles08

Wed Oct 28, 2009 4:16 am
Forum: Problem Solving
Topic: probability that they are matching shoes?
Replies: 7
Views: 6032

Very good solutions I did mine a bit differently. we can say a,b,c,d are 4 consecutive prime numbers. a*b*c = 4199 b*c*d = 7429 by a quick look we can see that both numbers are not divisible by 2,3, or 5 since the numbers are not even, do not add up to a multiple of 3 or don't have a 5 or 0 at the e...

by ssmiles08

Mon Oct 05, 2009 3:34 pm
Forum: Problem Solving
Topic: prime numbers
Replies: 6
Views: 1261

Let total inters = 100 75 percent of total interns who had less than 6 hours of sleep were tired. 80 percent of total interns had fewer than 6 hours of sleep which means 5 percent of interns who had less than 6 hours of sleep. if 80 percent of total interns had fewer than 6 hours of sleep, 20 percen...

by ssmiles08

Sun Oct 04, 2009 5:44 pm
Forum: Problem Solving
Topic: MGMAT CAT Question
Replies: 2
Views: 912

The area is 1/2 (AB) (AC) Sin 120 = 1/2 * 2 * 2 sin120 = 2 sin120 =root 3 U used trignometry ????? You can draw a line bisecting 120 degree triangle, which make two 30-60-90 triangles. hypotenuse is 2, base is sqrt(3) 2*base = 2sqrt(3) height = 1 (1/2)*[sqrt(3)]*1 = sqrt(3)

by ssmiles08

Sun Oct 04, 2009 2:19 pm
Forum: Problem Solving
Topic: Simple geometry quest
Replies: 3
Views: 959

I did'nt understand the last part// Got it till here...1/2^6 x 10^-3 If you got it till 1/2^6 x 10^-3, then all you need to do is multiplication and division. 2^6 = 64 1/64 ~ .015 round it up to .02 if you want...the numerator's exact number does not matter. .02 = 2/100 10^-3 = 1/1000 2/100 * 1/100...

by ssmiles08

Fri Oct 02, 2009 5:30 am
Forum: Problem Solving
Topic: how many zeros
Replies: 3
Views: 1457

1 / (2^9 * 5^3) can also be re-written as 1 / (2^6 *2^3 * 5^3)

1 / [2^6*(2^3 * 5^3)] = 1/2^6 * 1/10^3

1/1000 = .001 = 2 zeros.

1/2^6 = 1/64 (quick division tells you that the quotient is .01xyz)

so it 1/64 = .01 = 1/100

1/100 * 1/1000 = 1/100000 = .00001 = 4 zeros

IMO B.

by ssmiles08

Thu Oct 01, 2009 5:08 pm
Forum: Problem Solving
Topic: how many zeros
Replies: 3
Views: 1457

The radius of the circle is 10, so the distance would be the circumference of the circle which is 20pi.

2(t + 10) + 3t - 12 = 20pi

5t + 8 = 20pi

t = 4pi - 1.6

the time for car B is t + 10 since its already been on the road for 10 more hours.

4pi - 1.6 + 10 = 4pi + 8.4 (B)

by ssmiles08

Wed Sep 30, 2009 5:57 am
Forum: Problem Solving
Topic: rates and circles
Replies: 6
Views: 2174

IMO C too. The question seems a bit weird to me though.

by ssmiles08

Tue Sep 29, 2009 4:53 pm
Forum: Problem Solving
Topic: Remainder
Replies: 3
Views: 935

I kind of did it manually too...i don't know if your method is the same as mine. 30! consists of all numbers from 1 to 30. to find the highest power of 3, we need to know how many factors of 3 there are in 30! I wrote down all factors of 3 till 30 (broken down into primes as well) b/c this question ...

by ssmiles08

Tue Sep 29, 2009 4:45 pm
Forum: Problem Solving
Topic: Is there easy way of finding power of number in this scenari
Replies: 6
Views: 1265

I got asqrt(3) + asqrt(2) + a DA = a AD = a traingle ADE would be a 90-45-45 triangle. so AE = asqrt(2) Line CD bisects AB so since ABC is an equilateral triangle, AC = 2a. Line CD = asqrt(3) since triangle ADC is a 30-60-90 triangle. CD = asqrt(3) ED = a so CE = asqrt(3) - a triangle ACE = aqrt(3) ...

by ssmiles08

Sat Sep 26, 2009 9:35 am
Forum: Problem Solving
Topic: geometry problem
Replies: 4
Views: 1016

2^92 = (2^10)^9 * 2^4

if you know your powers of 2; you know that 2^10 is 1024

1024 gives you a remainder of 2 when divided by 7

2^9 = 512

512/7 gives you a remainder of 1

2^2 gives you a remainder of 4

1*4 = 4

remainder = 4.

by ssmiles08

Sat Sep 26, 2009 7:55 am
Forum: Problem Solving
Topic: Remainder problem
Replies: 5
Views: 2184

Let A to B = upstream. Which means B to A is downstream. The Streamer has its own rate with which it moves (+ or - the rate of the current) Let d = distance. Upstream: (r-c)*(9/2) = d; it is r - c b/c the streamer is flowing against the current and therefore the total rate would be the rate of the s...

by ssmiles08

Fri Sep 25, 2009 7:11 am
Forum: Problem Solving
Topic: Distance Problem - Upstream/Downstream/Current Speed
Replies: 5
Views: 11848

man I am surprised the test centers were even open in Atlanta! anyway you definitely made the best out of the situation and came out on top! congrats and good luck for your apps! :)

by ssmiles08

Thu Sep 24, 2009 6:04 pm
Forum: I just Beat The GMAT!
Topic: The Day the Rain Gods and Cops Conspired!
Replies: 4
Views: 1626

let x + y + z + v = 360 (sum of all angles in a quad) 1) Insufficient. Two right angles will give you 360-180 = 180. if x and y were right angles, z + v = 180. one of the angles does not have to be 60 degrees. 2) Insufficient. x = 2y. that still leaves us with 2y + y + z + v = 360 Together, there ar...

by ssmiles08

Thu Sep 24, 2009 10:37 am
Forum: Data Sufficiency
Topic: angles of a quadrilateral
Replies: 2
Views: 1188