This question was asked in CSIR _NET 2014. I cannot figure out what are conditions given:

Lunch-dinner pattern of a person for '$m$' days is given below. He has a choice of a vegeterian food and non-vegetarian food for his lunch or dinner. The pattern below given should be considered.

A. If he takes non-vegetarian lunch then he will have to take only vegetarian for dinner.

B. He takes non-vegetarian dinner for exactly for nine days.

C. He takes vegetarian lunch for exactly $15$ days.

D. He takes a total of $14$ non-vegetarian meals.

Determine the value of $m$.


2 Answers 2


Denote by $LN$ and $LV$ the numbers of non-vegetarian and vegetarian lunches, and by $DN$ and $DV$ the corresponding numbers of dinners.

  • Statement B implies $DN=9$
  • Statement C implies $LV=15$
  • Statement D impies $LN+DN=14$.

Then $LN=(LN+DN)-DN=14-9=5$. Furthermore,

  • the total number of days in this lunch/dinner schedule is $m=LN+LV=5+15=20$,
  • and finally we get $DV=m-DN=20-9=11$.

Hence the answer is


if the person eats lunch and dinner on every day. Otherwise, we can only conclude that



Let the number of days in which the person had non-veg lunch and veg dinner be $x$, veg lunch and non-veg dinner $y$ and two veg meals $z$. Then:

$y$ = 9
$y+z$ = 15
$x+y$ = 14

$x+y+z = m$ = 20


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