The students of X - B arranged a picnic.  The budget for food was Rs1600.  Because 8 students of the class failed to go, the cost of food to each student got increased by Rs.10.
How many students are there in class X - B ?

Asked by lahari lahari | 4th Nov, 2014, 05:13: PM

Expert Answer:

L e t space t h e space n u m b e r space o f space s t u d e n t s space b e space n. L e t space t h e space a v e r a g e space b e space apostrophe a apostrophe. T o t a l space a m o u n t space equals R s space 1600.  N u m b e r space o f space s t u d e n t s cross times A v e r a g e equals 1600 rightwards double arrow n cross times a equals 1600  N u m b e r space o f space s t u d e n t s space cross times A v e r a g e space equals 1600 rightwards double arrow left parenthesis n minus 8 right parenthesis cross times left parenthesis a plus 10 right parenthesis equals 1600 rightwards double arrow n a plus 10 n minus 8 a minus 80 equals 1600 rightwards double arrow 1600 plus 10 n minus 8 a minus 80 equals 1600 rightwards double arrow 10 n minus 80 equals 8 a rightwards double arrow 10 n minus 80 equals 8 cross times 1600 over n rightwards double arrow n left parenthesis 10 n minus 80 right parenthesis equals 8 cross times 1600 rightwards double arrow 10 n squared minus 80 n minus 12800 equals 0 rightwards double arrow n squared minus 8 n minus 1280 equals 0 rightwards double arrow n squared minus 40 n plus 32 n minus 1280 equals 0 rightwards double arrow n left parenthesis n minus 40 right parenthesis plus 32 left parenthesis n minus 40 right parenthesis equals 0 rightwards double arrow left parenthesis n minus 40 right parenthesis left parenthesis n plus 32 right parenthesis equals 0 therefore n equals 40 comma minus 32 T h e r e space a r e space 40 space s t u d e n t s space i n space c l a s s space X minus B

Answered by Prasenjit Paul | 5th Nov, 2014, 10:46: AM