For itemized tax returns in the $60,000-$75,000 income group for the most recent year reported, the average charitable contribution was $1935. Assume a normal distribution and a standard deviation of $400.
a. For a randomly selected household from this income group, what is the probability that the household made charitable contributions of at least $1600?
b. For a randomly selected household from this income group, what is the probability that the household made charitable contributions of between $2200 and $2400?
c. What level of contributions was exceeded by only 20% of the itemized returns in this income group?
d. What level of contributions was exceeded by 40% of the itemized returns in this income group?