600 Q48 V25 - Need Help :(

[subzero123]

Gave the test last week and fumbled. Was hoping for 650+ (preferably 700+) but ended up with 600 only.

Quant: I usually get between 48-50 in my practise tests.... be it OG or paper based and was feeling confident until I hit the 3rd question. I dont remember the exact question but it was something like this. What is the ratio of number of 5 digit words to the number of 4 digit words formed from a unique character set of 10 digits ? I figured out that the answer would be 10C5 / 10C4. When I solved the equation the ratio came to 6:5; something that I wasnt able to see as a valid choice on the paper. I recalculated it but got the same answer everytime. I spend long time trying to get it correct as it was my 3rd question and didnt want to guess it. Later I had to guess before moving on. This had a tough impact on me from the very first and I was tried to race against the time from then on. I finished the quant section with 10 secs to spare. That way I'm satisfied with my score of 48. I agree that the Quant is time consuming compared to OG or PP. The questions are wordy and can be very tricky.

The verbal section is what put me down. I was doing better in all the practise tests that I took getting around 39-41 in PPs and paper based tests. I thought I did the verbal well in the actual GMAT and was expecting my score to be in the range of 35-40. I was shocked to see my verbal score of 25 and it left me very dissappointed. I dont know what went wrong but I guess something surely did. I dont even know what brought my scores down. Whether it was SC, that I thought was pretty much similar to OG or was it RC & CR, that were bit tough than OG. Now please bail me out guys as I give the 2nd attempt in 3 weeks time. Please tell me what I need to do in order to ace the verbal this time. Any help will be very very sincerely appreciated.

Thanks,
SZ

[lipisruti]

Hello, subzero,

Don't blame yourself, the GMAT verbal qns are real curveballs and every test gives new results ..

I have three suggestions :

1. Get Kaplan Verbal (Red) Book and go through the Appendices. Try to use their rules in your own sentences (grade 3 stuff basically)
2. Then try last few qns in OG and spend equal time reading the answers in next five days.
3. If you are a science person, you may benefit from reading a simple magazine like Discover. Try current and back issues if available. Otherwise just go for the current issue of Discover and read the whole of it a couple of times.

Esp do the discover mag part last 2 days before test. Don't stress.

Hope it helps,

[subzero123]

Thanks lipisruti for the invaluable suggestion. Can someone tell me which is better apart from OG to improvise on one's verbal score ? I have both Princeton verbal and Kaplan verbal. I really want to give a good shot this time. Please pass your valuable suggestion !

Actual GMAT question:

Q) What is the ratio of number of 5 digit words to the number of 4 digit words formed from a unique character set of 10 digits ? I figured out that the answer would be 10C5 / 10C4. When I solved the equation the ratio came to 6:5; something that I wasnt able to see as a valid choice on the paper. Can anyone throw more light ?

Regards,
SZ

[manish2003]

Originally posted by subzero123
Actual GMAT question:

Q) What is the ratio of number of 5 digit words to the number of 4 digit words formed from a unique character set of 10 digits ? I figured out that the answer would be 10C5 / 10C4. When I solved the equation the ratio came to 6:5; something that I wasnt able to see as a valid choice on the paper. Can anyone throw more light ?

Regards,
SZ

Since the question does not say, we can assume repetition is allowed here. In that case total number of 5 digit words will be 10x10x10x10x10 and 4 digit words will be 10x10x10x10. So ratio will be simply
100000/10000 = 10:1

Another possibility is that even if repetition is not allowed, we need to take permutations, not just combinations. In that case answer will be
10P5/10P4 = (10!/5!)/(10!/6!) = 6:1

Does it make sense?

- Manish

[subzero123]

I forgot to mention that the question didn't allow for repetition. I still dont understand how 10P5 / 10P4 became (10!/5!)/(10!/6!) ?

I think it should be (10!/5!)/(10!/4!) ---- right ?

Someone please explain if I am missing something !

Regards,
SZ

[mick167]

Someone please explain if I am missing something !

OK
Let me explain it in other way

abc - 3 digit word

How many DIFFERENT 2 digit sub words
ab
ba

bc
bc

ac
ca

= 6 = (2C3 * 2! ) = 3! = 2P3

You made no difference between "ab" and "ba" when you said that there 2C3 words.

HTH!


How was RC? What they were about? How long were they?

[manish2003]

Originally posted by subzero123

I forgot to mention that the question didn't allow for repetition. I still dont understand how 10P5 / 10P4 became (10!/5!)/(10!/6!) ?

I think it should be (10!/5!)/(10!/4!) ---- right ?

Someone please explain if I am missing something !

Regards,
SZ

In general when order does not matter, we use C notation and when it does matter, we use P notation:

nCr = n!/(r!(n-r)!)

nPr = n!/(n-r)!

- Manish

[dkpbus]

Guys, This question is not that tough. Yes, It's tricky. Here is the solution

Five digit number from 10 digits (0,1,2,3,4,5,6,7,8,9)
OK..
Repeatition is not allowed.
OK..
Total 5-d number that can be formed will be = 9 * 10C4
Why 9 here -
See first place can be filled in 9 ways only. You can't use 0. If you use 0 in first place then it'll be a four digit number e.g. - 02345 = 2345 which is a 4-Digit no not 5.

Got it!
Similarily, No. of 4-Digit = 9*10C3

Ratio = 9*10C4/9*10C3 = 7/4

And that's answer.

[hellogmat]

Hello Guys,
I think manish2003 is right. The answer should be 10P5/10P4 = 10x9x8x7x6/10x9x8x7 = 6:1
Simple permutations here since the order matters and repetition is not allowed. The original question could be confusing because it uses the word "digits" to mean "letters".
dkpbus would have been right if the original question truly meant "digits" and "numbers" instead of "words".

[subzero123]

Thanks everyone for replying. I understand - how the same problem should be solved differently using "digits" instead of using "characters". For the records the actual question was based on "characters". Coming to Verbal, I guess it is getting harder. Getting a score of mid 30's seems increasingly tougher. Last week it was me, then "aaaa" and now "rahuliit". We all were expecting a score in the range of mid 30's in verbal but find ourselves only in mid 20's. Whats your thought on it Erin ? Have anyone taken the GMAT offlate and scored more than 35+ ?? I would love to hear from you as well.

Regards,
SZ

Regards
SZ