Final answer:
The error interval for a number x rounded to 6.3 to one decimal place is 6.25 ≤ x < 6.35, representing the range of numbers that would round to 6.3.
Step-by-step explanation:
When Cynthia rounds a number x to one decimal place and gets 6.3, the error interval for x will indicate the range of numbers that could be rounded to 6.3. Considering the rules of rounding to one decimal place, any number from half of one tenth less than 6.3 up to, but not including, half of one tenth more than 6.3 will be rounded to 6.3.
Therefore, the error interval can be written as:
6.25 ≤ x < 6.35
This range represents the range of numbers that, when rounded to one decimal place, would yield 6.3. Here, 6.25 is the lower bound and 6.35 is the upper bound of the error interval.