Consider a spinner that after a spin will point to a number

Question

1) Suppose that is normally distributed with a mean of 20 and a standard deviation of 3. What is P(16.91 ≤x≤ 24.59)?

2) The length of time needed to complete a certain test is normally distributed with mean 31 minutes and standard deviation 6 minutes. Find the probability that it will take less than 40 minutes to complete the test.

3) Find a value of c so that P(Z ≤ c) = 0.52.

4) Consider a spinner that, after a spin, will point to a number between zero and 1 with "uniform probability". Determine the probability: P(¹⁄₆ ≤ X ≤ ¹⁷⁄₃₀).