In another model of radioactive decay, a student fills a burette with water, as shown in the diagram, and starts a timer at the instant the tap at the
bottom is opened. She notes the height of the column of water at regular
intervals. It takes 35 seconds to empty from 50 ml to 25 ml. Assuming that
the arrangement provides a good model of radioactive decay:
a How long will it take for three quarters of the water in the burette to drain
away?
b How much water should remain in the burette after 134 minutes?