Question 128

An alloy contains copper, zinc and nickel in the ratio of 5 : 3 : 2. The quantity of nickel in kg that must be added to 100 kg of this alloy to have the new ratio 5 : 3 : 3 is

Solution

initial ratio of copper, zinc and nickel is 5 : 3 : 2. let the amount of copper be 5y and zinc be 3y and nickel be 2y

let the amount nickel added be z

new ratio of copper, zinc and nickel is 5 : 3 : 3 and total weight of alloy is (100+z)

as the value of zinc is same in both cases, we can write

$$\frac{5}{11} x (100+z) = \frac{5}{10} x 100$$

1000 +10z = 1100

z= 100/10 = 10 kg

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