Normal distribution, Z-Score and Probability Help.

I'm having a difficult time trying to answer these questions. Any help would be very helpful.

The time it takes a randomly selected job applicant to perform a certain task has a normal distribution with mean 120 seconds and standard deviation 12 seconds.

1. We are interested in computing the probability that it takes a randomly selected job applicant more than 135 seconds to perform a task. Compute the Z-Score.

2. Find the probability in question #1.

3. The fastest 10% are to be given advanced training. What task time qualifies individuals for advanced training?


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I'm so sorry.

Well here is what I got and if somebody could tell me if I am going in the right direction.



z=135-120/12 = 1.25


using the z table, i went to 1.2 then to .5 and got .8944


I'm not sure how to work it, I'm not really even comprehending this question. 10% of what number?

Thank you all so much for taking time to help me out. I just want to know if I am doing these correctly.