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Finding the Fourth Proportional to 691.20, 1,030.80 and 662.40

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Solution

The fourth proportional to 691.20, 1,030.80 and 662.40 is: 987.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.20 : 1,030.80 = 662.40 : x
  2. Step 2: Convert to fraction form
    691.20/1,030.80 = 662.40/x
  3. Step 3: Cross multiply
    691.20x = 1,030.80 × 662.40
  4. Step 4: Simplify right side
    691.20x = 682,801.92
  5. Step 5: Solve for x
    x = 682,801.92/691.20
  6. Step 6: Final answer
    x = 987.85

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.