The time required to finish a test is normally distributed with a mean of 60 minutes and a standard deviation of 10 minutes. What is the z-Score for a student who finishes the test in 45 minutes?

Question

kropot72 · Answer

$$z=\frac{X-\mu}{\sigma}=\frac{45-60}{10}=$$
Can you finish the calculation?

anonymous · Answer

0.06681

anonymous · Answer

?

kropot72 · Answer

$$z=\frac{45-60}{10}=\frac{-15}{10}=?$$
Can you finish it correctly now?

kropot72 · Answer

You are confusing the calculation of z with the probability of finishing the test in fewer than 40 minutes. The value of z is -1.5. The probability of finishing the test in fewer than 40 minutes is 0.0668.