The U. S. no longer uses silver and gold in coins because a. gold and silver lost too much value in the 1960s to be used as coin money.
b. the U. S. decided to convert to the platinum standard and back all money with platinum.
c. it is cheaper for the government to produce coins without silver and gold.
d. copper became more valuable than silver and could be used in its place.

Anew 2-lane road is needed in a part of town that is growing. at some point the road will need 4 lanes to handle the anticipated traffic. if the city's optimistic estimate of growth is used, the expansion will be needed in 4 years and has a probability of happening of 40%. for the most likely and pessimistic estimates, the expansion will be needed in 8 and 15 years respectively. the probability of the pessimistic estimate happening is 20%. the expansion will cost $ 4.2 million and the interest rate is 8%. what is the expected pw the expansion will cost?