Task: Question Answering
Input (English): Problem: one pipe can fill a pool 1.25 times faster than a second pipe . when both pipes are opened , they fill the pool in 4 hours . how long would it take to fill the pool if only the slower pipe is used ? 
Options: a ) 11.25 , b ) 11.52 , c ) 1.25 , d ) 9 , e ) 7.2
Output (English): d