Abacterial culture is known to grow at a rate proportional to the amount present after 1 hour, 1000 strands of the bacteria are observed in the culture, and after 4 hours, 3000 strands. find the number of strands of bacteria originally in the culture.

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?