Question

The owner of an organic fruit stand also sells nuts. She wants to mix cashews worth $5.50 per pound with peanuts worth $2.30 per pound to get a 1/2 pound mixture that is worth $2.80 per pound. How much of each kind of nut should she include in the mixed bag?

Answer 1

Total weight required is half pound, so let the amount of cashews be
`a` , and amount of peanuts be $b$

$\therefore a+b=0.5$ (1)

And we want this to cost $2.80$

Cost of $a$ pound of cashews will be $5.50\times a$ and cost of $b$ pound peanuts will be $2.30\times b$

$\therefore 5.5a+2.3b=2.8$ (2)

Substitute $a=0.5-b$ from equation (1) in equation (2)

$5.5(0.5-b)+2.3b=2.8$

$\implies -3.2b=2.8+5.5\times0.5 $

$\implies -3.2b=0.05$

$b$ comes out to be negative. That means there's no solution with the given conditions.

I checked once , I don't think there's any mistake. Can someone else verify too?

EDIT

I verified all the given options from calculator, and no option gives 2.80