David works at a science lab that conducts experiments on bacteria. The population of the bacteria multiplies at a constant rate, and his job is to notate the population of a certain group of bacteria each hour. At 1 p.m. on a certain day, he noted that the population was 2,500 and then he left the lab. He returned in time to take a reading at 4 p.m., by which point the population had grown to 160,000. Now he has to fill in the missing data for 2 p.m. and 3 p.m. What was the population at 3 p.m.?
Pick.
A) 45,000  B) 40,000  C) 50,000  D) 55,000  E) 60,000
let the rate be x, then population of the bacteria after each hour can be given as 2500, 2500x, 2500(x^2), 2500(x^3)   now population at 4pm =160,000   thus we have 2500(x^3) = 160,000 =64   thus x=4   therefore population at 3pm = 2500(16) = 40,000   Answer : 40,000
<result>B</result>
David works at a science lab that conducts experiments on bacteria. The population of the bacteria multiplies at a constant rate, and his job is to notate the population of a certain group of bacteria each hour. At 1 p.m. on a certain day, he noted that the population was 2,500 and then he left the lab. He returned in time to take a reading at 4 p.m., by which point the population had grown to 160,000. Now he has to fill in the missing data for 2 p.m. and 3 p.m. What was the population at 3 p.m.?