Question

A number x, rounded to 1 decimal place is 12.3 write down the error interval for x

Answer 1

We know that
A number x, rounded to 1 decimal place is 12.3
so
x>=12.25
and
x < 12.35

the error interval for x is the interval [12.25,12.35)

the answer is
[12.25,12.35)