GMAT in 2 days, couple of questions

Question

Hi everyone, There are a few problems I don't know to solve from GMAT Prep, could you please kindly help me? Test is on saturday and pressure is increasing

Thanks in advance !

shilpiruchi · Answer

Lots to type :-D

Let me try to handle one question at a time. Here goes the first one. Ques 1 : Jar containing red, blue and white marbels Solution 1 - The ques : Is the prob of getting red > prob of getting white OR is the no of red> no of white For sufficiency : the ans should be ALWAYS YES or ALWAYS NO For Insufficiency – SOMETIMES YES SOMETIMES NO Lets assume 2 numbers - Case 1:w>r (which wud mean the chances of picking white will be more) red=5; blue=5; white=10 Case 2: r>w (which wud mean chances of picking red will be more) red=10 ;blue =5, white =5 Statement 1: (Refer to the highlight while ans the ques) substitute the values from case 1 – inequality doesn't hold true => thus red has to be more than white and ans to the ques is YES from case 2 – inequality holds true => thus red has to be more than white and ans to the ques is YES Since ALWAYS YES → statement 1 is sufficient; choice B, C, E gone Statement 2:(Refer to the highlight while ans the ques) substitute the values from case 1 – inequality doesn't hold true => thus red has to be more than white and ans to the ques is YES from case 2 – inequality holds true => thus red has to be less than white and ans to the ques is NO SOMETIMES YES SOMETIMES NO => Insufficient Ans :A Confirm : If you try to plug with equal numbers of white and red in Statement 1, it will not hold true proving that it cant be equal either and thus prob cant be same for both.

shilpiruchi · Answer

Q 2 : Quadrilateral DS

Ques is :  IS atleast one of the interior angles 60?

Fact: Sum of all the internal angles of a quadrilateral ABCD is 360 degrees
Refer to the highlighted question when answering for each case

Statement 1 :

2 are 90 degrees. 
if, the other 2 are 90 each => ans is YES
if, one is 60 other 120 => ans is NO
Sometimes Yes, sometimes No => INSUFFICIENT

Choice A,D gone

(If 3 angles are 90, then rectangle. Remember perfect square bottom can have a tilted edge on top in the quadrilateral)

Statement 2 :

if, ABC is 50 degrees; BCD is 100 degrees but the other 2 can be
60 and 150 => ans is YES
90 and 120 => ans is NO
Sometimes Yes, Sometimes No => INSUFFICIENT

Choice B gone

Insufficient & Insufficient => Lets try Together
if 2 are 90 degrees, other can be 45 and 135 => ans is NO
or 2 are 90 and other can be 60 and 120 => ans is YES
Sometimes Yes, Sometimes No => INSUFFICIENT

Answer is  E

KarishmaB · Answer

Question 1:

The probability that red marble is chosen will be greater than the probability that white marble is chosen if there are more red marbles than white marbles.
So the question is just: Is r > w

Statement 1: r/(b + w) > w/(b + r)

Cross multiply to get r(b + r) > w(b + w) ...

Now, if r > w, (b + r) has to be greater than (b + w) and the inequality will hold.

If r were less than w, then (b + r) < (b + w) and the left side would have been smaller than the right side. Hence r cannot be less than w because it is given to us that the left side is greater than the right side.

So this implies that r must be greater than w. Sufficient.

Statement 2: b > r + w
But we cant compare r and w so not sufficient.

Answer (A).

KarishmaB · Answer

Question 3: x and y are not integers. Value of x is closest to which integer?

1. 4 is the integer closest to x+y
2. 1 is the integer closest to x-y

Statement 1: Since x+y is closest to 4, 
3.5 < x+y < 4.5
No information about x alone.
Statement 2: Since x-y is closest to 1,
0.5 < x-y < 1.5
No information about x alone.

Using both together, add both the inequalities to get rid of y.
3.5 + .5 < x + y + x - y < 4.5 + 1.5
2 < x < 3
The value of x lies between 2 and 3 but we do not know whether it is closer to 2 (e.g. 2.3) or closer to 3 (e.g. 2.7). Hence not sufficient.

Answer E

KarishmaB · Answer

Question 4: Alice's take home pay.

I am putting down the Algebra solution (since you have the test tomorrow) though usually I would not do that. I would just skip to the options and plug them in to see what works.

Algebra: Say, her take home pay is $100 a month. She saves s every month and spends 100-s
At the end of the year, she saves 12s.
Given: 12s = 3(100-s)
s = 20
She saved 20/100 = 1/5 every month.

I would usually just try to plug in numbers. Say, if she saves 1/4 every month, she will have 12/4 = 3 at the end of the year. But this should be 3 times 3/4 which it isn't so 1/4 is too much. Go down a little.
Try 1/5. At the end of the year, she would have 12/5. She spends 4/5 every month. 12/5 is 3 times of 4/5 so got it!

KarishmaB · Answer

Question 5: s and t on number line

Make sure you read the question stem very very carefully tomorrow. 
It says 's and t are two different numbers on the number line.'

Statement 1 tells you that distance between s and 0 is same as distance between t and 0. If s and t were on the same side of 0, they would be the same number. That is unacceptable. Hence they must be on different sides and one of them must be the negative of the other. Therefore, their sum must be 0.

Statement 2 just says that 0 is between s and t. It doesn't say it is right in the middle. s could be -2 and t could be 5 etc.

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