After an hour, the population of bacteria with a number of P0 found that their number became 3 / 2P0. If the growth rate is proportional to the number of bacteria (P (t) present at time t, find the time required for the number of bacteria to 3 times.

A radioactive material decays at a rate which is proportional to the amount of radioactivity remaining. If the amount of radioactivity remaining is denoted by N at the time t, form an equation which represents this statement. If the half-life (the time taken for half the radioactivity to decay) is 10 years, how long will it take for ¾ of the radioactivity to decay?

The doubling period of a bacterial population is 1010 minutes. At time t=90t=90 minutes, the bacterial population was 70000.What was the initial population at time t=0?   What is the size of the bacterial population after 4 hours?

Initially 47 grams of radioactive substance was present. After 10 hours the mass had decreased by 10%. If the rate of decay is proportional to the amount of the substance present at a time t, find the amount remaining after 60 hours.