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Finding the Fourth Proportional to 390.68, 585.90 and 143.85

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Solution

The fourth proportional to 390.68, 585.90 and 143.85 is: 215.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.68 : 585.90 = 143.85 : x
  2. Step 2: Convert to fraction form
    390.68/585.90 = 143.85/x
  3. Step 3: Cross multiply
    390.68x = 585.90 × 143.85
  4. Step 4: Simplify right side
    390.68x = 84,281.72
  5. Step 5: Solve for x
    x = 84,281.72/390.68
  6. Step 6: Final answer
    x = 215.73

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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.