The answer to how many more hours Sierra needs depends on the total number of hours required for the accredited program to become a medical lab assistant. Since that specific number isn't provided in your question, I'm unable to calculate how many more hours she needs without it.
If you have that total number, you can subtract the 165 hours Sierra has already completed from the total to find out how many more hours she requires. For example:
If the total requirement is \( X \) hours, then: \[ \text{Hours needed} = X - 165 \]
Could you provide the total hours required for her program?