One pipe can fill a tank three times as fast as another pipe. If together the two pipes can fill tank in 40 min, then the slower pipe alone will be able to fill the tank in?	Select:
A) 160 B) 787 C) 144 D) 128 E) 121
Let the slower pipe alone fill the tank in x min.   Then, faster pipe will fill it in x/3 min.   1/x + 3/x = 1/40   4/x = 1/40 =&gt; x = 160 min.   160nswer: 160
<result>A</result>
One pipe can fill a tank three times as fast as another pipe. If together the two pipes can fill tank in 40 min, then the slower pipe alone will be able to fill the tank in?