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Statement 1: When x is rounded to the nearest thousandth the result is 0.455.

Two cases.

Case 1: Thousandths digit is 5 (0.4550 <= x < 0.4555). Then x rounded to the nearest hundredth would be 0.46. Case 2: Thousandths digit is 4 (0.4545 < x < 0.4550). Then x rounded to the nearest hundredth would be 0.45.

Therefore, insufficient.

Statement 2: The thousandths digit of x is 5.

Doesn't give any information about any of the other digits of x. Insufficient.

Evaluting Both Statements.

Since we know that the thousandths digit of x is 5, this falls under Case 1. X rounded to the nearest hundredths digit if 0.46. Therefore, sufficient.

What is the result when x is rounded to the nearest hundredth? 1) When x is rounded to the nearest thousandth the result is 0.455. 2) The thousandths digit of x is 5.

Isn't 0,455 rounded 0,46?

No. If the thousandths digit is 4, e.g. 0.4549, the nearest thousandth is 0.455 and the nearest hundredth is 0.45 If the thousandths digit is 5, e.g. 0.4551, the nearest thousandth is 0.455 and the nearest hundredth is 0.46.

Therefore we need the information from (2) to state that x rounded to the nearest hundredth is 0.46, so the answer is C.

Re: GMAT Prep DS: When X is rounded [#permalink]
02 Jan 2010, 08:14

c.. (1) when x is rounded to the nearest thousandth, the result is .455 .... means the no could be .4546 or .4552... ans in first case will be .45 and in 2nd case .46 not suff.. (2) the thousandths digit of x is 5 .... nothing given abt hundredths digit.... not suff combined we know the no is .4551,.4552,.4553,.4554... in each case ans is .46 so hundredth digit is 6...suff hope it helped!

But I still feel the OA should A. Look at the Q. What is the result after X rounded off to nearest hundredth ie. Two digits after the decimal. As explained by many, it is possible to ans this using only Statement 1 as follows: Cases: 1. If the number is 0.4549 after rounding off to nearest hundredth it is 0.46 2. If the number 0.455 after rounding off to nearest hundredth it is 0.46 3. If the number 0.455 after rounding off to nearest hundredth it is 0.46 In any of the above cases the final rounding number remains same ie. 0.455. Is my logic correct or am I missing something?

But I still feel the OA should A. Look at the Q. What is the result after X rounded off to nearest hundredth ie. Two digits after the decimal. As explained by many, it is possible to ans this using only Statement 1 as follows: Cases: 1. If the number is 0.4549 after rounding off to nearest hundredth it is 0.46 2. If the number 0.455 after rounding off to nearest hundredth it is 0.46 3. If the number 0.455 after rounding off to nearest hundredth it is 0.46 In any of the above cases the final rounding number remains same ie. 0.455. Is my logic correct or am I missing something?

Red part is not correct: 0.4549 rounded to the nearest hundredth = 0.45, since the first dropped 4 is less than 5.

Rounding rules

Rounding is simplifying a number to a certain place value. To round the decimal drop the extra decimal places, and if the first dropped digit is 5 or greater, round up the last digit that you keep. If the first dropped digit is 4 or smaller, round down (keep the same) the last digit that you keep.

Example: 5.3485 rounded to the nearest tenth = 5.3, since the dropped 4 is less than 5. 5.3485 rounded to the nearest hundredth = 5.35, since the dropped 8 is greater than 5. 5.3485 rounded to the nearest thousandth = 5.349, since the dropped 5 is equal to 5.

Re: GMAT Prep DS: When X is rounded [#permalink]
27 Oct 2011, 19:58

1

This post received KUDOS

Expert's post

Responding to a pm:

When you round off to the hundredth digit, you look at only the thousandth digit i.e. you focus only on the next digit.

Say x = .4546 When you round it to the nearest hundredth digit, you get x = .45 (not .46). The reason is that the thousandth digit is 4 which is less than 5. 0.4546 is closer to 0.45 than it is to 0.46 You do not follow a sequence of roundings to arrive at x = .455 and then x = .46

Say x = .4553 Now when you round to the nearest hundredth, you get x = .46 because the thousandth digit is 5. .4553 is closer to .46 than to .45

Therefore statement 1 is not sufficient alone. If you round off x to thousandth and get .455, you do not know whether x was .4546 or .4553 initially (or similar). Hence you do not know what you will get when you round it to nearest hundredth. Statement 2 tells you that the thousandth digit was 5 so now you know that x was .4553 (or similar) and it will be rounded to .46
_________________

Re: GMAT Prep DS: When X is rounded [#permalink]
28 Oct 2011, 20:26

Karishma , I may be little off on this one but as per stm1 : whatever was the value of X , when it was rounded to nearest thousandth it became .455 so when i round this to nearest hundredth shoudn't it become .46 ?

suppose X was .4549 so when it is rounded(round up ) to the nearest thousandth it becomes .455 and when finally rounded to nearest hundredth it becomes .46

suppose X was .4554 so when it is rounded( round down) to the nearest thousandth it becomes .455 and when finally rounded to nearest hundredth it becomes .46

Am is missing something here ? can you please elaborate a bit as to why both statements are needed.

I guess , my Question is why should we bother about the digit after the Thousandth digit when stmt1 clearly says that the thousandth digit (post round off) is 5 and asks about the Hundreth digit.

Re: GMAT Prep DS: When X is rounded [#permalink]
28 Oct 2011, 21:40

Expert's post

shashankp27 wrote:

Karishma , I may be little off on this one but as per stm1 : whatever was the value of X , when it was rounded to nearest thousandth it became .455 so when i round this to nearest hundredth shoudn't it become .46 ?

suppose X was .4549 so when it is rounded(round up ) to the nearest thousandth it becomes .455 and when finally rounded to nearest hundredth it becomes .46

suppose X was .4554 so when it is rounded( round down) to the nearest thousandth it becomes .455 and when finally rounded to nearest hundredth it becomes .46

Am is missing something here ? can you please elaborate a bit as to why both statements are needed.

I guess , my Question is why should we bother about the digit after the Thousandth digit when stmt1 clearly says that the thousandth digit (post round off) is 5 and asks about the Hundreth digit.

When you have to round a number to the hundredth, you do not have to first round it off to thousandth and then to hundredth. You have to directly round it off to the hundredth. Forget process. Think logic. Is 0.4549 closer to .45 or .46? It is closer to 0.45 so you will round it off to 0.45 The digit right next to the last digit you want is the only important one. It is incorrect to round off numbers in steps. If you want to round off till hundredth, it has to be done in a single step.
_________________

Re: GMAT Prep DS: When X is rounded [#permalink]
18 Jun 2013, 07:59

Expert's post

VeritasPrepKarishma wrote:

Responding to a pm:

When you round off to the hundredth digit, you look at only the thousandth digit i.e. you focus only on the next digit.

Say x = .4546 When you round it to the nearest hundredth digit, you get x = .45 (not .46). The reason is that the thousandth digit is 4 which is less than 5. 0.4546 is closer to 0.45 than it is to 0.46 You do not follow a sequence of roundings to arrive at x = .455 and then x = .46

Say x = .4553 Now when you round to the nearest hundredth, you get x = .46 because the thousandth digit is 5. .4553 is closer to .46 than to .45

Therefore statement 1 is not sufficient alone. If you round off x to thousandth and get .455, you do not know whether x was .4546 or .4553 initially (or similar). Hence you do not know what you will get when you round it to nearest hundredth. Statement 2 tells you that the thousandth digit was 5 so now you know that x was .4553 (or similar) and it will be rounded to .46

Hi Karishma, So answer would be C I think...Please confirm!
_________________

Re: GMAT Prep DS: When X is rounded [#permalink]
18 Jun 2013, 08:30

Expert's post

debayan222 wrote:

VeritasPrepKarishma wrote:

Responding to a pm:

When you round off to the hundredth digit, you look at only the thousandth digit i.e. you focus only on the next digit.

Say x = .4546 When you round it to the nearest hundredth digit, you get x = .45 (not .46). The reason is that the thousandth digit is 4 which is less than 5. 0.4546 is closer to 0.45 than it is to 0.46 You do not follow a sequence of roundings to arrive at x = .455 and then x = .46

Say x = .4553 Now when you round to the nearest hundredth, you get x = .46 because the thousandth digit is 5. .4553 is closer to .46 than to .45

Therefore statement 1 is not sufficient alone. If you round off x to thousandth and get .455, you do not know whether x was .4546 or .4553 initially (or similar). Hence you do not know what you will get when you round it to nearest hundredth. Statement 2 tells you that the thousandth digit was 5 so now you know that x was .4553 (or similar) and it will be rounded to .46

Hi Karishma, So answer would be C I think...Please confirm!

Re: GMAT Prep DS: When X is rounded [#permalink]
18 Jun 2013, 08:48

Expert's post

debayan222 wrote:

VeritasPrepKarishma wrote:

Responding to a pm:

When you round off to the hundredth digit, you look at only the thousandth digit i.e. you focus only on the next digit.

Say x = .4546 When you round it to the nearest hundredth digit, you get x = .45 (not .46). The reason is that the thousandth digit is 4 which is less than 5. 0.4546 is closer to 0.45 than it is to 0.46 You do not follow a sequence of roundings to arrive at x = .455 and then x = .46

Say x = .4553 Now when you round to the nearest hundredth, you get x = .46 because the thousandth digit is 5. .4553 is closer to .46 than to .45

Therefore statement 1 is not sufficient alone. If you round off x to thousandth and get .455, you do not know whether x was .4546 or .4553 initially (or similar). Hence you do not know what you will get when you round it to nearest hundredth. Statement 2 tells you that the thousandth digit was 5 so now you know that x was .4553 (or similar) and it will be rounded to .46

Hi Karishma, So answer would be C I think...Please confirm!