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Finding the Fourth Proportional to 758.80, 1,138.20 and 691.60

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Solution

The fourth proportional to 758.80, 1,138.20 and 691.60 is: 1,037.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    758.80 : 1,138.20 = 691.60 : x
  2. Step 2: Convert to fraction form
    758.80/1,138.20 = 691.60/x
  3. Step 3: Cross multiply
    758.80x = 1,138.20 × 691.60
  4. Step 4: Simplify right side
    758.80x = 787,179.12
  5. Step 5: Solve for x
    x = 787,179.12/758.80
  6. Step 6: Final answer
    x = 1,037.40

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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.