Chapter 6.2, Problem 9E

A random variable is normally distributed with a mean of $\mu =50$ and a standard deviation of $\sigma =5$ .
  a. Sketch a normal curve for the probability density function. Label the horizontal axis with values of 35, 40, 45, 50, 55, and 65. Figure 6.4 shows that the normal curve almost touches the horizontal axis at three standard deviations below and at three standard deviations above the mean (in this case at 35 and 65).
  b. What is the probability that the random variable will assume a value between 45 and 55?
  c. What is the probability that the random variable will assume a value between 40 and 60?