A club has to buy x gold medals, y silver medals and z bronze medals for an event. When the prices of gold, silver and bronze medals are $30, $20 and $10 each respectively, the total cost is $410. When the prices are $40, $25 and $15 each respectively, the total cost is $545.

(a) Find two possible sets of values of x, y and z.

(b) Do you think the solutions you have obtained are the only possible sets? Give your reasons.

1 answer

To solve this problem, we can set up a system of equations.

Let's use the variables x, y, and z to represent the number of gold, silver, and bronze medals, respectively.

From the problem, we can set up the following equations:

30x + 20y + 10z = 410 (Equation 1)
40x + 25y + 15z = 545 (Equation 2)

To solve this system of equations, we can use substitution or elimination method. Let's use substitution method here.

Solving Equation 1 for x, we get:

x = (410 - 20y - 10z) / 30 (Equation 3)

Substitute Equation 3 into Equation 2:

40((410 - 20y - 10z) / 30) + 25y + 15z = 545

Simplifying this equation gives us:

(4100 - 200y - 100z + 1500y + 900z) / 30 = 545

Combine like terms:

(5800 + 1300y + 800z) / 30 = 545

Multiply both sides by 30:

5800 + 1300y + 800z = 545 * 30

5800 + 1300y + 800z = 16350

Rearrange the equation:

1300y + 800z = 10550 (Equation 4)

Now we have a system of two equations (Equation 3 and Equation 4) with two variables (y and z). We can solve this system to find the possible sets of values for x, y, and z.

(a) One possible solution:

From Equation 4, we can see that z must be a multiple of 50 to get an integer value for y. Let's try z = 50:

1300y + 800(50) = 10550
1300y + 40000 = 10550
1300y = -29450
y = -22.65

Since y cannot be a negative value, this solution is not possible.

Another possible solution:

Let's try z = 0:

1300y + 800(0) = 10550
1300y = 10550
y = 8.12

Since y cannot be a decimal value, this solution is not possible either.

Therefore, there are no possible sets of values for x, y, and z that satisfy both equations.

(b) Based on the calculations above, we can conclude that the solutions obtained are the only possible sets of values.