<PRE><B>Question 712437</B>
9 days left to go, with 10 more students, the consumption rate is 50% FASTER.  This is and intuition suggests 6 days.  The now 30 students will finish the food remaining in 6 days instead of 9 days.


Also there is rate time job relationship.  The job is consuming the remaining 9-day food. 

Count Students______rate_________days_________job
20 students_________1/9__________9____________1
30 students________1.5/9________( 6 )_________1


{{{t=1/(1.5/9)}}}
{{{t=9/1.5}}}
{{{t=6}}} days.</PRE>