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Finding the Fourth Proportional to 390.76, 586.17 and 385.40

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Solution

The fourth proportional to 390.76, 586.17 and 385.40 is: 578.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.76 : 586.17 = 385.40 : x
  2. Step 2: Convert to fraction form
    390.76/586.17 = 385.40/x
  3. Step 3: Cross multiply
    390.76x = 586.17 × 385.40
  4. Step 4: Simplify right side
    390.76x = 225,909.92
  5. Step 5: Solve for x
    x = 225,909.92/390.76
  6. Step 6: Final answer
    x = 578.13

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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.