7. Mr. and Mrs. Spark have had problems starting their two cars during the cold winter
months. They decided to record the number of times each car starts during a one month
period in the winter. They attempted to start each car every morning for thirty days and
recorded the following information.
• The first car started 20 times.
• The second car started 18 times.
Both cars started 40% of the time.
What is the probability that on any particular morning during the month
a) at least one of the cars starts?
b) they cannot start either of the two cars?