Final answer:
The second brand of mixed nuts contained 25% peanuts. This was determined by using the weighted average calculation to solve for the unknown percentage in the mixture equation.
Step-by-step explanation:
To determine the percentage of peanuts in the second brand of mixed nuts, we can set up an equation based on the weighted average formula. Since Shreya made a nut mixture that contains 43% peanuts by mixing 9 lbs. of mixed nuts (with 75% peanuts) and 16 lbs. of a different brand, we can express this mathematically as:
(9 lbs × 75% + 16 lbs × x%) / (9 lbs + 16 lbs) = 43%
Where 'x' represents the percentage of peanuts in the second brand of mixed nuts. Solving for 'x' we get:
(675 + 16x) / 25 = 43
675 + 16x = 43 × 25
16x = 1075 - 675
16x = 400
x = 400 / 16
x = 25
So, the second brand of mixed nuts contained 25% peanuts.