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Finding the Fourth Proportional to 1,218.20, 1,681.10 and 666.20

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Solution

The fourth proportional to 1,218.20, 1,681.10 and 666.20 is: 919.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.20 : 1,681.10 = 666.20 : x
  2. Step 2: Convert to fraction form
    1,218.20/1,681.10 = 666.20/x
  3. Step 3: Cross multiply
    1,218.20x = 1,681.10 × 666.20
  4. Step 4: Simplify right side
    1,218.20x = 1,119,948.82
  5. Step 5: Solve for x
    x = 1,119,948.82/1,218.20
  6. Step 6: Final answer
    x = 919.35

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.