12. In Problem 3, suppose Lawrence, a typical citizen, has the utility function
U(m, d, h) = m + 7d2 − d2 − 4h, where d is the number of hours per day that he spends driving around,
h is the average number of hours per day spent driving around by other people in his home town, and
m is the amount of money he has left to spend on other stuff besides gasoline and auto repairs. Gas and
auto repairs cost $1 per hour of driving. If each citizen believes that their own driving will not affect
the amount of driving done by others, they will all drive D1 hours per day. If all citizens drive to
maximize the utility of a typical citizen, they will all drive D2 hours per day, where
13. In Problem 3, suppose Sam, a typical citizen, has the utility function U(m, d, h) = m + 13d2 − d2 − 6h,
where d is the number of hours per day that he spends driving around, h is the average number of
hours per day spent driving around by other people in his home town, and m is the amount of money
he has left to spend on other stuff besides gasoline and auto repairs. Gas and auto repairs cost $1 per
hour of driving. If each citizen believes that their own driving will not affect the amount of driving
done by others, they will all drive D1 hours per day. If all citizens drive to maximize the utility of a
typical citizen, they will all drive D2 hours per day, where
14. In Problem 3, suppose Albert, a typical citizen, has the utility function U(m, d, h) = m + 5d2 − d2 − 2h,
where d is the number of hours per day that he spends driving around, h is the average number of
hours per day spent driving around by other people in his home town, and m is the amount of money
he has left to spend on other stuff besides gasoline and auto repairs. Gas and auto repairs cost $1 per
hour of driving. If each citizen believes that their own driving will not affect the amount of driving
done by others, they will all drive D1 hours per day. If all citizens drive to maximize the utility of a
typical citizen, they will all drive D2 hours per day, where