8 pounds of peanuts has to be mixed with cashews
SOLUTION:
Given that , we have to find how many pounds of peanuts costing $3.00 a pound should be mixed with 4 pounds of cashews costing $4.50 a pound to obtain a mixture costing $3.50 a pound?
Now, let the weight of peanuts be n pounds.
Then, according to given information,
cost of m pounds of peanuts = 3.60m
cost of n pounds of cashews = 4 x 4.50 = $ 18
now, total weight of mixture = n + 4
then, total cost of mixture = 3.50(n + 4)
now we also know that, total cost of mixture = cost of peanuts + cost of cashews
3.50(n + 4) = 3n + 18
3.50n + 14 = 3n + 18
3.50n – 3n = 18 – 14
0.5n = 4
n = 8
Hence, 8 pounds of peanuts has to be mixed with cashews.