1) The population of a small city was 41 000 in 1970 and 47 000 in 1978. Predict the population for 1995. Assume exponential growth and state the final answer to the nearest thousand.

2)A population of bacteria, growing exponentially, quadruples its number in four hours. How long does it take for the number of bacteria to be 1.5 times of the original number?

3)The value of an oil company's common shares increases at a rate proportional to its present value. Assuming exponential growth, the present value of $21 is expected to increase to $25 in one year. When will it be worth $40? (State your answer to the nearest whole number.)