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Finding the Fourth Proportional to 782.60, 1,173.90 and 691.40

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Solution

The fourth proportional to 782.60, 1,173.90 and 691.40 is: 1,037.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    782.60 : 1,173.90 = 691.40 : x
  2. Step 2: Convert to fraction form
    782.60/1,173.90 = 691.40/x
  3. Step 3: Cross multiply
    782.60x = 1,173.90 × 691.40
  4. Step 4: Simplify right side
    782.60x = 811,634.46
  5. Step 5: Solve for x
    x = 811,634.46/782.60
  6. Step 6: Final answer
    x = 1,037.10

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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.