An isotope of the element erbium has a half-life of approximately 12 hours. Initially there are 13 grams of the isotope present. a. Write the exponential function that relates the amount of substance remaining, A(t) measured in grams, as a function of t, measured in hours.

Television viewing reached a new high when the global information and measurement company reported a mean daily viewing time of 8.35 hours per household. use a normal probability distribution with a standard deviation of 2.5 hours to answer the following questions about daily television viewing per household. a. what is the probability that a household views television between 4 and 10 hours a day? (to 4 decimals) b. how many hours of television viewing must a household have in order to be in the top 7% of all television viewing household? (to 2 decimals) c. what is the probability that a household views television more than 4 hours a day? (to 4 decimals)