A stock market investment: A stock market investment of $10,000 was made in 1970. During the decade of the 1970s, the stock lost half its value. Beginning in 1980, the value increased until it reached...

A stock market investment: A stock market investment of $10,000 was made in 1970. During the decade of the 1970s, the stock lost half its value. Beginning in 1980, the value increased until it reached $35,000 in 1990. After that its value has remained stable. Let v = v(d) denote the value of the stock, in dollars, as a function of the date d.

a. What are the values of v(1970), v(1980), v(1990), and v(2000)?

b. Make a graph of v against d. Label the axes appropriately.

c. Estimate the time when your graph indicates that the value of the stock was most rapidly increasing.