How do I calculate the sample data that falls within the interval? It says from the interval 425.5 - 454.5

This should be 95% of the population data within the interval (according to empirical rule). The question states I SHOULD expect 95%, but the answer is 92.22%. Why is it 92.22 and not 95? how do I calculate this?

*also I understand I did not provide the table of values as it was really large, I just want a rough estimate on how could I make this calculation. I've been stuck on it for a few hours.