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Re: d = 0.43t7 If t denotes the thousandths digit in the decimal [#permalink]
13 Jul 2012, 17:11

Expert's post

amit82 wrote:

Just a query- is 5 rounded up or down? Or is it left as it is?

Posted from my mobile device

If the first dropped digit is 5 (or greater), ROUND UP the last digit that you keep.

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.

If t denotes the thousandths digit in the decimal representation of d above, what digit is t?

(1) If d were rounded to the nearest hundredth, the result would be 0.44. Just says that t\geq{5}. Not sufficient. (2) If d were rounded to the nearest thousandth, the result would be 0.436. Since 7 is more than 5, then t was rounded up to become 6, hence t=5. Sufficient.

Re: d = 0.43t7 If t denotes the thousandths digit in the decimal [#permalink]
28 Nov 2012, 10:37

Bunuel wrote:

amit82 wrote:

Just a query- is 5 rounded up or down? Or is it left as it is?

Posted from my mobile device

If the first dropped digit is 5 (or greater), ROUND UP the last digit that you keep.

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.

If t denotes the thousandths digit in the decimal representation of d above, what digit is t?

(1) If d were rounded to the nearest hundredth, the result would be 0.44. Just says thatt\geq{5}. Not sufficient. (2) If d were rounded to the nearest thousandth, the result would be 0.436. Since 7 is more than 5, then t was rounded up to become 6, hence t=5. Sufficient.

Answer: B.

Hope it's clear.

I agree with your answer but... for bold above... t can also take a value of 4 right? because we got a 7....

Re: d = 0.43t7 If t denotes the thousandths digit in the decimal [#permalink]
29 Nov 2012, 03:26

Expert's post

Amateur wrote:

Bunuel wrote:

amit82 wrote:

Just a query- is 5 rounded up or down? Or is it left as it is?

Posted from my mobile device

If the first dropped digit is 5 (or greater), ROUND UP the last digit that you keep.

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.

If t denotes the thousandths digit in the decimal representation of d above, what digit is t?

(1) If d were rounded to the nearest hundredth, the result would be 0.44. Just says thatt\geq{5}. Not sufficient. (2) If d were rounded to the nearest thousandth, the result would be 0.436. Since 7 is more than 5, then t was rounded up to become 6, hence t=5. Sufficient.

Answer: B.

Hope it's clear.

I agree with your answer but... for bold above... t can also take a value of 4 right? because we got a 7....

No, that's not correct. When we are rounding to the nearest hundredth, only thousandth digit matters since it's the first dropped digit (check example in my previous post).

Thus, 0.43t7 rounded to the nearest hundredth to be 0.44, t must be more than or equal to 5.

Re: If t denotes the thousandths digit in the decimal [#permalink]
29 Nov 2012, 11:34

yup, I thought we need to round off 7 first and then the thousandth digit to round hundredth.... the process which you said, is it just employed in GMAT or in general too? thanks for clarifying....

Re: If t denotes the thousandths digit in the decimal [#permalink]
30 Nov 2012, 03:03

Expert's post

Amateur wrote:

yup, I thought we need to round off 7 first and then the thousandth digit to round hundredth.... the process which you said, is it just employed in GMAT or in general too? thanks for clarifying....

This is a general rule, not only for the GMAT.
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