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Finding the Fourth Proportional to 761.28, 1,139.90 and 518.28

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Solution

The fourth proportional to 761.28, 1,139.90 and 518.28 is: 776.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    761.28 : 1,139.90 = 518.28 : x
  2. Step 2: Convert to fraction form
    761.28/1,139.90 = 518.28/x
  3. Step 3: Cross multiply
    761.28x = 1,139.90 × 518.28
  4. Step 4: Simplify right side
    761.28x = 590,784.78
  5. Step 5: Solve for x
    x = 590,784.78/761.28
  6. Step 6: Final answer
    x = 776.04

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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.