Task: Question Answering
Input (English): Problem: at 1 : 00 pm , there were 10.0 grams of bacteria . the bacteria increased to x grams at 4 : 00 pm , and 25.6 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 ? 
Options: a ) 15.1 , b ) 15.4 , c ) 15.7 , d ) 16.0 , e ) 16.3
Output (English): d