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IMO A 1) sufficient given y=x+5 (10x+(x+5)r)/(x+x+5)=12 10x+(x+5)r=24x+60 14x+60=rx+5r x=5r-60/14-r now x must be a number(non negative and r>12) only possible value of r in the equation is 13 which gives us x=5 y=10 r=13 2) NOT sufficient 10x+y^2=12x+12y which has two variables na man u got it wro...

by tohellandback

Wed Feb 09, 2011 3:57 am
Forum: Data Sufficiency
Topic: pumpkins
Replies: 20
Views: 5087

IMO E

1) INSUFF: the point x can lie in region m,9m,90m and also 900m upto <500m

2) INSUFF:same reasoning..the point x can lie in region m,9m,90m and also 900m upto <495m

combined:same reasoning

by tohellandback

Fri Apr 23, 2010 11:42 am
Forum: Data Sufficiency
Topic: Math problem
Replies: 11
Views: 1270

elimination:

let x is 50.

put it in the answer options..you should get 60. A,B and E are easily eliminated.

put x=25

put x in C and E.you should get 120.
answer is E

by tohellandback

Thu Apr 22, 2010 2:56 am
Forum: Problem Solving
Topic: algebraic approach?
Replies: 5
Views: 1096

IMO C 1) NOT sufficient 2) NOT SUFF combined 1<sqrt(n)<2 so the square root is not an integer. the number is not an integer. tohellandback, I think it wouldn't be advisable to assume that since the sqrrt of a number is not integer, the number itself is also not an integer. As you would agree that t...

by tohellandback

Wed Sep 30, 2009 9:57 pm
Forum: Data Sufficiency
Topic: Is n an integer?
Replies: 11
Views: 1439

IMO C 1) NOT sufficient 2) NOT SUFF combined 1<sqrt(n)<2 so the square root is not an integer. the number is not an integer. tohellandback, I think it wouldn't be advisable to assume that since the sqrrt of a number is not integer, the number itself is also not an integer. As you would agree that t...

by tohellandback

Wed Sep 30, 2009 9:35 pm
Forum: Data Sufficiency
Topic: Is n an integer?
Replies: 11
Views: 1439

IMO C

1) NOT sufficient
2) NOT SUFF

combined
1<sqrt(n)<2
so the square root is not an integer. the number is not an integer.

by tohellandback

Wed Sep 30, 2009 9:23 pm
Forum: Data Sufficiency
Topic: Is n an integer?
Replies: 11
Views: 1439

Re: Permutations Questin

Four married couples have bought 8 seats in the same row for a concert. In how many different ways can they be seated a. With no restrictions? b. If each couple is to sit together c. If all the men sit together on the right of all the women. THANKS> a) 8! b) 4!*(2!*2!*2!*2!) because the four couple...

by tohellandback

Wed Sep 30, 2009 9:18 pm
Forum: Problem Solving
Topic: Permutations Questin
Replies: 2
Views: 751

IMO A

Paul,Jane,Joan
Paul,Jane,Jessica
Stuart,Joan,Jessica

by tohellandback

Tue Sep 29, 2009 8:16 pm
Forum: Problem Solving
Topic: Committee
Replies: 5
Views: 1324

thanks for confirming. but the way i did it was a little different. 130 prime factors - 2,5,13. no of divisors is multiplication of (powers of each +1) 2x2x2 = 8. If we got a larger number then this method is easier I believe? I think your method is better than one stated above.. the other method c...

by tohellandback

Tue Sep 29, 2009 8:11 pm
Forum: Problem Solving
Topic: Number properties PS
Replies: 5
Views: 1040

Re: To the power 4

If x^4 + y^4 = 100 greatest value of x is between A. 0 and 3 B. 3 and 6 C. 6 and 9 D. 9 and 12 E. 12 and 15 The answer has to be either A or B, but which would you choose. IMO B to maximize x^4 minimize y^4 y=0 for x=3, x^4=81 for x=4, x^4= 256 so x must be greater than 3 but less than 4 only B sat...

by tohellandback

Sun Sep 06, 2009 10:11 pm
Forum: Problem Solving
Topic: To the power 4
Replies: 8
Views: 1063

in one of the 4 subject we have 3/4 * 400=300 students
minimum in any subject is 20
to maximize the number of seniors in one of the other two subject, minimize one of them
so one of the other two has 20
remaining=80
B

by tohellandback

Sun Sep 06, 2009 6:44 pm
Forum: Problem Solving
Topic: greatest possible number of seniors
Replies: 5
Views: 2294

for these questions: 1) check whether you have 3 or 7 in the denominator 2) see if they cancel out with 3's or 7's in numerator In case there are big numbers involved, check for bigger prime numbers too. But I am yet to see a question where u need to check for numbers >7 A. 10/189-denominator has 3*...

by tohellandback

Thu Sep 03, 2009 10:16 pm
Forum: Problem Solving
Topic: Recurring decimal....tough one
Replies: 5
Views: 1047

Let income is I dollars
he saves X dollars this year
next year he will have X(1+r) dollars

X(1+r)=(I-X)/2
X(1+r)=I/2-X/2
X+Xr+X/2=I/2
X(3/2+ r)=I/2
X/I= 1/2r+3

Answer E

by tohellandback

Thu Sep 03, 2009 10:08 pm
Forum: Problem Solving
Topic: Challenging one
Replies: 3
Views: 864

I guess we can do this w/o calculation.

if each month he had received 750, hen the average wud be 750. He received 30*20 =600 hundred dollars extra.
this 600 dollars must be divided into 26 parts to egt the average.600/26= 23.something
answer is 750+23=773

by tohellandback

Tue Sep 01, 2009 6:48 pm
Forum: Problem Solving
Topic: Can you do this problem w/o any calculation?
Replies: 2
Views: 1261

since X is negative
|x|=-x
sqrt(-x|x|)= sqrt(-x*-x)=sqrt(x^2)=|x|=-x
Answer A


sqrt(x^2) = |x| is a rule

by tohellandback

Tue Sep 01, 2009 6:41 pm
Forum: Problem Solving
Topic: if x<0, then (-x|x|)^1/2 is what?
Replies: 6
Views: 5903