At 1:00 pm, there were 10.0 grams of bacteria. The bacteria increased to x grams at 4:00 pm, and 16.9 grams at 7:00 pm. If the amount of bacteria present increased by the same fraction during each of the 3-hour periods, how many grams of bacteria were present at 4:00 pm?	Pick
A) 13.0
B) 13.3
C) 13.6
D) 13.9
E) 14.2
Let x be the factor by which the bacteria increases every three hours.   At 4:00 pm, the amount of bacteria was 10x and at 7:00 pm it was 10x^2.   10x^2 = 16.9   x^2=1.69   x=1.3   At 4:00 pm, the amount of bacteria was 10(1.3)=13 grams.   The answer is 13.0.
<result>A</result>
At 1:00 pm, there were 10.0 grams of bacteria. The bacteria increased to x grams at 4:00 pm, and 16.9 grams at 7:00 pm. If the amount of bacteria present increased by the same fraction during each of the 3-hour periods, how many grams of bacteria were present at 4:00 pm?