AMOUNT OF BACTERIA PRESENT
Time Amount
1:00 P.M. 8.0 grams
4:00 P.M. x grams
7:00 P.M. 12.4 grams
Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.? Options:	A) 12.0	B) 12.1	C) 12.2	D) 10.0	E) 10.4
The question says that bacteria increased by same fraction, not by same amount in 2 intervals of 3 hours.   Let X represent the amount of bacteria present at 4:00 PM. Since the fractional increase must remain constant from 1 to 4pm as it is from 4pm to 7pm:   Fractional increase from 1 PM to 4 PM = X / 8.0   Fractional increase from 4 PM to 7 PM = 12.4 / X   X \ 8 = 12.4 \ X   X^2 = 12.4 * 8   X = 10   answer : 10.0
<result>D</result>
AMOUNT OF BACTERIA PRESENT
Time Amount
1:00 P.M. 8.0 grams
4:00 P.M. x grams
7:00 P.M. 12.4 grams
Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?