1) Find the missing value for the radioactive isotope. (Round your answer to two decimal places.)

Isotope	Half-life (years)	Initial Quantity	Amount after 1000 years
239Pu	24,100		2.9 g

2) The number of bacteria in a culture is increasing according to the law of exponential growth. After 2 hours, there are 50 bacteria, and after 5 hours, there are 400bacteria. How many bacteria will there be after 7 hours?

3) Use the Richter scale

R = log I/I0

for measuring the magnitudes of earthquakes. Find the magnitude R of each earthquake of intensity I (let I₀ = 1). (Round your answers to two decimal places.)

(a) I = 110,800,000 R = (b) I = 44,419,000 R = (c) I = 14,000 R =

Determine the principal P that must be invested at rate r = 3%%, compounded monthly, so that $500,000 will be available for retirement in t = 13 years. (Round your answer to the nearest cent.) Use the Richter scale I R log Io for measuring the magnitudes of earthquakes. . Find the magnitude R of each earthquake of intensity I (let I0 = 1). (Round your answers to two decimal places.) (a) I = 110,800,000 R = D (b) I = 44,419,000 R : U (c) I = 14,000 R = U