The amount that people spend per month on entertainment follows a normal distribution with a mean of $175 and standard deviation of $40. What is the probability that a person spends less than $149.80 per month on entertainment? (round to 4 decimal places, for example 0.1234)

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?