SOLUTIONRounding 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.
For more check Number Theory chapter of Math Book:
math-number-theory-88376.htmlBACK TO THE ORIGINAL QUESTION:
d = 0.43t7
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.
Answer: B.
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