Question

The total cost of 10 erasers and 5 sharpner is at least RS.65.The cost of each eraser cannot exceed Rs.4.Find the minimum cost of each sharpner.

Answer 1

Cost of 10 erasers & 5 sharpners
$\to$ at least R.65
Cost of each eraser cannot exced Rs.4
$\therefore$ Minimum cost of each sharpner
Let, price of each eraser =x & price of each sharpner =y
$\therefore 10x+5y>65$
Also, $y<4$
$\Rightarrow 5y<5\times 4=20$
$\therefore$ Max. cost of 5 sharpners = 20Rs.
$\therefore 10x>65-5y$
This can be minimum only when 5y is maximum.
$\to 10x>65-20\Rightarrow 10x>45\Rightarrow x>4.5$
$\therefore$ Minimum cost of each sharpner is Rs. 4.5