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
Quote:
Does it mean that its always necessary to know the orignial value if X in this case and not the rounded value?
Responding to a pm:
You do need the original value to get the "further rounded" value in this case. But it will not always be so.
If you are given that rounded to the nearest thousandth, x = 0.452.
Here, it doesn't matter what the original value of x is.
Rounded to the nearest hundredth, the value of x will be 0.45.
Why? Because the actual value of x could be something like 0.4517 or 0.4523. The thousandth digit will be either 1 or 2. In either case, the hundredth digit will remain 5.
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Karishma
Veritas Prep GMAT Instructor
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