Let the required amount of mixed nuts be n pounds.
Here, the price of trail mix, which is $4.95 /lb, is the weighted average of the price of n lb mixed nuts and 10 lb dried fruits.
∴$4.95 /lb=(n×4.75)+(10×5.50)(n+10)
⇒4.95×(n+10)=(n×4.75)+(10×5.50)(n+10)×(n+10)
⇒4.95n+49.5=4.75n+55
⇒4.95n+49.5−4.75n−49.5=4.75n+55−4.75n−49.5
⇒(4.95−4.75)n=55−49.5
⇒0.20n=5.5
⇒2n=55
(Multiplying both sides of the equation by 10)
⇒n=552=27.5
(Dividing both sides of the equation by 2)
∴ 27.5 pounds ––––––––––––––of mixed nuts worth $4.75 /lb should be combined with 10 lb of dried fruits worth $5.50 /lb to make a trail mix that would sell for $4.95 /lb.