In the decimal 3.1de, d and e each represent a digit. If x

Question

In the decimal 3.1de, d and e each represent a digit. If x represents the decimal 3.1de rounded to the nearest tenth, what is the value of x?

(1) d=4 
(2) e=8

Bunuel · Accepted Answer

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.

BACK TO THE ORIGINAL QUESTION:
 In the decimal 3.1de, d and e each represent a digit. If x represents the decimal 3.1de rounded to the nearest tenth, what is the value of x?

According to the rule above the tenth digit of x depends only on d, since it's the first dropped digit.

(1) d=4. Our decimal is 3.14e --> the first dropped digit is 4, so less than 5, hence 3.14e rounded to the nearest tenth is 3.1. Sufficient.

(2) e=8. Clearly not sufficient.

Answer: A.

Hope it's clear.

ankitbansal85 · Answer

1. d=4..
so the number is 3.14e...... we are suppose to round off to the nearest tenth....so tenth digit is 4 which will be rounded off to 3.1....we are not bothered about e.

2. e= 8

Here the number can be 3.118 whcih will be rounded off to 3.1 or 3.158 which will be rounded off to 3.2......as we are not sure of the value of d we are not sure ...it can have different values.

so the correct answer is A

vikram4689 · Answer

We need to find out whether d belongs to 0-4 category or 5-9 category. We get this from i) but not from ii). So, A

ga99 · Answer

Shouldn't the answer be C: both needed to answer.

Since d is 4 as per statement 1, the approximation also depends on e. If e=0 - 4, then x is 3.1. If e=5 - 9, then the x is 3.2. e would not matter only if d < 4.

ga99 · Answer

Its clear now. I was always rounding based on all the digits from right to left and not taking just the first dropped digit. 
For e.g. in your example of "5.3485 rounded to the nearest tenth = 5.3, since the dropped 4 is less than 5." I would always have picked 5.4 I now see how that might not work.
Thanks for the explanation. I overlooked this while preparing.

krrish · Answer

dude here is the logic if d = 4, then when u round it, we do get a value of 3.2 so its sufficient
2. s2 is not sufficient. 
hence a is fine

GMATinsight · Answer

CONCEPT : TO round off a number at any place we only need to know the next place digit i.e. to round off tenth we need Hundredth, To round off Hundredth we need only Thousandth digit and so on...

If next place is 0 to 4 then the digit to be rounded off remains same
If next place is 5 to 9 then the digit to be rounded offis rounded up i.e. next digit

Question : 3.1de rounded to the nearest tenth=?

i.e. we only need to know the value of d

Statement 1 : d=4 
SUFFICIENT

Statement 2 : e=8 
NOT SUFFICIENT

Answer: option A

stonecold · Answer

Nice Question 
Here decimal=3.1de
rounding x to nearest tenths we will get either =>
3.1 for d=0,1,2,3,4
OR
3.2 fro d=5,6,7,8,9
Hence we need the value of d here
Statement 1 => sufficient => x=3.1
Statement 2 => no clue of d => not sufficient 
Hence A

Sri07 · Answer

Hi Bunuel,

We are given 3.1de, there are 2 values which will determine what the value of the tenths place

If D is greater than or equal to 5 then 3.1 will become 3.2 and whether or not D is greater than 5 will depend on the value of e. 
Therefore, I selected answer choice C.

Could you pls help understand why does the official answer ignore the presence of "e"

Bunuel · Answer

When rounding to the nearest tenth, only hundredth digit is important, you can ignore all other digits. Check again highlighted rules.

hiranmay · Answer

In the decimal 3.1de, d and e each represent a digit. If x represents the decimal 3.1de rounded to the nearest tenth, what is the value of

(1) d=4
(2) e=8

Folks,

could you clarify this question, I thought E but Gmat prep software says A. I am confused.

Thanks

anmolsd1995 · Answer

Shouldn't the answer be C ?

3.1de

if we choose A we still not know anything about e and since e is greater than 5 then it is rounded off to next big value

3.148 which will round off to 3.2 if we round it step by step.

can anyone explain flaw in my approach ?

Bunuel · Answer

Your doubt is addressed above. Please read the hole thread carefully before posting a question.

Basshead · Answer

(1) if d = 4, we can conclude that e must be 0, 1, 2, 3, or 4. 3.1de rounded to the nearest tenth is 3.1. SUFFICIENT.

(2) if e = 8, we don't know what the value of d is. x can be 3.1 or 3.2. INSUFFICIENT.

Answer is A.

bumpbot · Answer

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In the decimal 3.1de, d and e each represent a digit. If x

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In the decimal 3.1de, d and e each represent a digit. If x

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