1. If z varies jointly as x and y and z = 12 when x = 2 and y = 4 , find z when x = 5 and y = 2 .

2. If z varies jointly as x and y, and z = 24 when x = 3 and y = 4 find a when x = 3 and y = 2 .

3. If a varies jointly as c and d, and a = 20 when c = 2 and d = 4 find d when a = 25 and c = 8 .

4. If a varies jointly as c and d, and a = 15 when c = 4 and d = 5 find when a = 25 and d = 2

5. If z varies jointly as x and the square of y, and z = 20 when x = 4 and y = 2 find z when x = 2 and y = 4

6. If z varies jointly as x and the square of y, and z = 40 when x = 5 and y = 4 find z when x = 2 and y = 4

7. If z varies directly as x and inversely as y, and z = 16 when x = 3 and y = 2 find a when x = 5 and y = 3 .

8. If z varies directly as x and inversely as y and z = 12 when x = 2 and y = 5 , find z when x = 3 and y = 4

9. If z varies directly as the square of x and inversely as y, and z = 20 when x = 2 and y = 4 find z when x = 4 and y = 2

10. If z varies directly as the square of x and inversely as y, and z = 50 when x = 5 and y = 2 find z when x = 4 and y = 5

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