My z values doesn't have probability for 3

You're right to ask about that! Standard normal distribution tables (Z-tables) often provide probabilities for Z-values up to two decimal places, like $Z=2.99$. For $Z=3.00$ and higher, the probability is very close to 1, and sometimes tables will list it explicitly or you might need to infer it.

Here's how you typically find it:

• Standard Z-tables: Most standard Z-tables will have an entry for $Z=3.00$. You would look for 3.0 in the left-most column and 0.00 in the top row.
• Common Value: The probability $P(Z < 3)$ is a well-known value in statistics. It represents the area under the standard normal curve to the left of $Z=3$.
• Value Used: In the previous solution, we used $P(Z < 3) \approx 0.99865$. This is the correct value for the cumulative probability up to $Z=3$.

If your specific table doesn't show 3.00, it might show 2.99 as the highest value, which is 0.9986. For practical purposes, 0.99865 (or 0.9987 if rounded to four decimal places) is the accurate value for $P(Z < 3)$.