Help with Quant questions

Question

Hi all.
Please help me with these questions.
I don't understand how they go to the answer. The ones that I got right was guess work.
Thank you for your help

ksp · Answer

3) Take common numbers from the column. You prephrase it as

1*( 1 -2 +3 -4 +5 -6 +7) + 2( 1 2 +3 -4 +5..+7) + 3*(..) + 4*(..) +..+ 7*(..)
=> 1*(4) + 2*(4) + 3*(4)+..7*(4) = 112

ksp · Answer

4. GCD(x,y ) * LCM(x,y) = X * Y --> RULE

ksp · Answer

5. initially k/b = 5/3

after the gift it becomes (5x - 10 ) / (3x +10) and this equals 7/5

on solving for x we get 30. 
substitue it in the eqn aftr gifting. k = 140 and b=100.

the diff = 40

ksp · Answer

6.

Option 1 . t<0. Clearly both t and k must be negative. So the kt is positive and hence to the right of t

Option 2. k<1. We have three options.
0<k<1. In this case kt will be in between k and t.
k=0. In this case it will be as same as k.
k<0. This can be negative if t is +ve. It can go to the right of t if both k and t are negative.

So clearly a.

ksp · Answer

2.

The given qstn can be re phrased as.

P ( white or even ) = P( white ) + P( even ) - P(white and even )

option 1. P(white and even ) =0
option 2. P(white) - P(even ) = 0.2

Hence not enough. E

ksp · Answer

1.

Take the full triangle.

L P +  L R +  L T = 180
 L R +  L T = 90. since  L P = 90. -------(1)

In isosceles triangle RQS,  L RSQ =  L RQS
Hence Sum of angles in triangle RQS 
 L R +  L RQS +  L RSQ = 180
 L R = 180 - 2( L RSQ) --------------(2) since  L RSQ =  L RQS

In isosceles triangle TUS, similarly
 L T = 180 - 2( L UST) ------------(3)

From the figure we know that,
 L UST +  L x +  L QSR = 180
 L QSR = 180 - x -  L UST -------------------(4)

Substitue (2) (3) and (4) in (1)
we get,
180 - 2* L QSR + 180 - 2*( L UST) = 90
360 - 2*( L QSR) - 2*(180 - x -  L UST) = 90
On cancelling it out,
2x = 90 alone remains.
x = 45.

Phew... !!

Patcheko80 · Answer

KSP.. You're the man.
I like the way you broke it down with explation.
I owe you one..

Thanks a lot .

My D-Day is December 3rd. I score a 45 on this GMAT Prep. I hope my D-Day I can score at least 48

ksp · Answer

Hey dude... Am no expert man... Am giving my gmat on nov 22. Me too in ur range.

One thing i noticed in similar problems like 1st qstn.

We need to first rephrase the entire triangle and then if we narrow down we will arrive at the answer. If we start from the unknown, then we will be lost. This approach helped me in many similar qstns.

Patcheko80 · Answer

Dude.. Expert or not, your input was really valuable.

Now I can focus on my verbal while still improving my quant.. Still can't score past 34 in verbal. RC's killing me.

ksp · Answer

For RC, for me the Kaplan strategy worked well. Giv it a try dude. I felt the time reduced greatly.

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