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Finding the Fourth Proportional to 1,287.92, 1,931.16 and 518

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Solution

The fourth proportional to 1,287.92, 1,931.16 and 518 is: 776.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.92 : 1,931.16 = 518 : x
  2. Step 2: Convert to fraction form
    1,287.92/1,931.16 = 518/x
  3. Step 3: Cross multiply
    1,287.92x = 1,931.16 × 518
  4. Step 4: Simplify right side
    1,287.92x = 1,000,340.88
  5. Step 5: Solve for x
    x = 1,000,340.88/1,287.92
  6. Step 6: Final answer
    x = 776.71

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.