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Finding the Fourth Proportional to 1,209.20, 1,813.74 and 428.96

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Solution

The fourth proportional to 1,209.20, 1,813.74 and 428.96 is: 643.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.20 : 1,813.74 = 428.96 : x
  2. Step 2: Convert to fraction form
    1,209.20/1,813.74 = 428.96/x
  3. Step 3: Cross multiply
    1,209.20x = 1,813.74 × 428.96
  4. Step 4: Simplify right side
    1,209.20x = 778,021.91
  5. Step 5: Solve for x
    x = 778,021.91/1,209.20
  6. Step 6: Final answer
    x = 643.42

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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.