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Finding the Fourth Proportional to 691.20, 1,036.80 and 446.40

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Solution

The fourth proportional to 691.20, 1,036.80 and 446.40 is: 669.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.20 : 1,036.80 = 446.40 : x
  2. Step 2: Convert to fraction form
    691.20/1,036.80 = 446.40/x
  3. Step 3: Cross multiply
    691.20x = 1,036.80 × 446.40
  4. Step 4: Simplify right side
    691.20x = 462,827.52
  5. Step 5: Solve for x
    x = 462,827.52/691.20
  6. Step 6: Final answer
    x = 669.60

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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.