The number of bacteria in a petri dish increased by 50 percent every 1 hour. If there were 108 million bacteria in the dish at 2: 00 p.m., at what time were there 32 million bacteria in the dish?
Choose one
A) 10: 00 a.m. B) 11: 00 a.m. C) 12: 00 p.m. D) 01: 00 p.m. E) 02: 00 p.m.
Given:   he number of bacteria in a petri dish increased by 50 percent every 1 hour   There were 108 million bacteria in the dish at 2: 00 p.m   Since the bacteria is increasing by 50% every 1 hour, this means that the number is multiplied by 1.5 every 1 hour.   Required: At what time were there 32 million bacteria in the dish?   Assume that there were n intervals of 1 hour between 32 million and 108 million.   32 * (1.5)^n = 108   (3/2)^n = 108/32 = 27/8 = (3/2)^3   Hence n = 3 intervals.   Each interval was of 1 hour. Therefore, the number of hours = 3   Subtracting 3 hours from 2 PM, we get 11 AM as the answer.   Option 11: 00 a.m.
<result>B</result>
The number of bacteria in a petri dish increased by 50 percent every 1 hour. If there were 108 million bacteria in the dish at 2: 00 p.m., at what time were there 32 million bacteria in the dish?