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Finding the Fourth Proportional to 792.90, 1,189.32 and 428.40

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Solution

The fourth proportional to 792.90, 1,189.32 and 428.40 is: 642.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    792.90 : 1,189.32 = 428.40 : x
  2. Step 2: Convert to fraction form
    792.90/1,189.32 = 428.40/x
  3. Step 3: Cross multiply
    792.90x = 1,189.32 × 428.40
  4. Step 4: Simplify right side
    792.90x = 509,504.69
  5. Step 5: Solve for x
    x = 509,504.69/792.90
  6. Step 6: Final answer
    x = 642.58

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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.