Answer:
8.635 ≤ x < 8.645
Step-by-step explanation:
When a measurement is expressed to a certain precision, it can be because it was rounded to that precision. Rounding up occurs from values that are equal to or greater than 5 in the place to the right of the right-most digit.
That is, the smallest value that will round up to 8.64 is 8.635.
Rounding down occurs from values that are less than 5 in that same number place. Any value less than 8.645 will round down to 8.64.
The boundaries of values that round to 8.64 are ...
8.635 ≤ x < 8.645
