*Rounding to decimals

[Guest]

I am not sure of the answer but i think its D only can any help me confirm this one please

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

Statement (1) alone is sufficient but (2) alone is not sufficient
Statement (2) alone is sufficient but (1) alone is not suifficent
Both statements together are sufficient but neither statement alone is sufficient
each statement alone is sufficient
statements (1) and (2) together are not sufficient

[P]

From statement (2) you don't know what the value of X is, the only thing you know about it
is that it has a 5 in the thousandth's place (._ _ 5). So I will go with answer A as statement one
gives you the approximate value for X.

[RonPurewal]

please post the source of this problem (per forum rules). if the source isn't posted within the next few days, we'll have to remove the thread.

this rule has always been important, but i'm sure you can understand its importance even more now that this whole scoretop scandal has broken.

sources! please! thank you!

[Arpitha]

I havent posted the question, but I know where it is from.
Source: GMAT Prep Test II

Less confusion had the question been added there!

[Guest]

From statement (2) you don't know what the value of X is, the only thing you know about it
is that it has a 5 in the thousandth's place (._ _ 5). So I will go with answer A as statement one
gives you the approximate value for X.

I have a query regrding this.

What is it was .4546 . In this case when rounded to hundreth , wont we get .45

I guess we need both A and B for this.

[esledge]

The answer is C, you do need both statements (1) and (2).

Here's the rule about rounding: If the digit after the intended last digit is 5 or greater, round up. If the digit after the intended last digit is 4 or less, round down, or simply truncate.

For example: To round 3.486 to the nearest hundredth, look at the thousandths place, which is 6, so we will round up to 3.49. To round 11.21 to the nearest tenth, look at the hundredths place, which is 1, so we will round down to 11.2.

(2) INSUFFICIENT: As "P" points out above, the 5 in the thousandths place does tell us to round up to the next hundredth, but we have no idea what that is.

(1) INSUFFICIENT: The previous poster got this right: x could be 0.4546, which would round up to 0.455 when rounding to the thousandths place (per the statement), but would round down to 0.45 when rounded to hundredths (one possible answer to the question). On the other hand, x could be 0.4551, which would round up to 0.455 when rounding to the thousandths place (per the statement), and would round up to 0.46 when rounded to hundredths (another possible answer to the question). The value of x rounded to the nearest hundredth could be 0.45 or 0.46.

(1) & (2) SUFFICIENT: 0.455 <= x < 0.456 (the inequality symbols are awkward to format here, so read them carefully)

The thousandths digit is 5 or greater for all of these values, therefore we will round up to the next hundreth: 0.46.

[Prakash]

Hi Emily,

"The previous poster got this right: x could be 0.4546, which would round up to 0.455 when rounding to the thousandths place (per the statement), but would round down to 0.45 when rounded to hundredths (one possible answer to the question). "

In the above statement,
0.4546 --> 0.455
0.455 --> 0.45(?).

Shouldn't 0.455 round to 0.46 as per your earlier statement?("If the digit after the intended last digit is 5 or greater, round up")

I'm sure I'm missing something here, would be great if you could clarify.

Thanks
Prakash

[RonPurewal]

Hi Emily,

"The previous poster got this right: x could be 0.4546, which would round up to 0.455 when rounding to the thousandths place (per the statement), but would round down to 0.45 when rounded to hundredths (one possible answer to the question). "

In the above statement,
0.4546 --> 0.455
0.455 --> 0.45(?).

Shouldn't 0.455 round to 0.46 as per your earlier statement?("If the digit after the intended last digit is 5 or greater, round up")

I'm sure I'm missing something here, would be great if you could clarify.

Thanks
Prakash

you're trying to perform the act of rounding in multiple steps, which is not allowed. ROUNDING IS A 1-STEP PROCESS.
in other words, if i tell you to round 145 to the nearest hundred, you say 100.
you don't pull some two-step mojo where you first round up to the nearest ten (150) and then round THAT to the nearest hundred (200). no way jose, not acceptable.

same deal with the decimals in this problem: if you're going to round 0.4546 to the nearest hundredth, do it in one step, producing 0.45.
save the two-step for the dance floor.