When a number $n$ is rounded to two decimal places and the result is 3.87, the actual value of $n$ could be slightly less or greater than 3.87 but still round to 3.87.

The error interval for $n$ can be described using the following inequalities:

$3.865 \leq n < 3.875$

This means:

• The smallest possible value of $n$ is 3.865, as anything smaller would round down to 3.86.
• The largest possible value of $n$ is just below 3.875, as 3.875 would round up to 3.88.

Do you want more details or have any questions?

Here are 5 related questions:

1. How would the error interval change if $n$ were rounded to 1 decimal place?
2. What would be the error interval for $n$ if the rounded result were 4.25 instead of 3.87?
3. How does rounding affect calculations in practical applications like finance or engineering?
4. What is the difference between rounding and truncating a number?
5. How can we calculate the error interval for numbers rounded to different decimal places?

Tip: When rounding a number to a certain decimal place, always identify the midpoint between two possible rounded values to define the error interval.