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Finding the Fourth Proportional to 387.12, 579.78 and 289.20

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Solution

The fourth proportional to 387.12, 579.78 and 289.20 is: 433.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    387.12 : 579.78 = 289.20 : x
  2. Step 2: Convert to fraction form
    387.12/579.78 = 289.20/x
  3. Step 3: Cross multiply
    387.12x = 579.78 × 289.20
  4. Step 4: Simplify right side
    387.12x = 167,672.38
  5. Step 5: Solve for x
    x = 167,672.38/387.12
  6. Step 6: Final answer
    x = 433.13

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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.