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Finding the Fourth Proportional to 421.83, 628.76 and 390.66

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Solution

The fourth proportional to 421.83, 628.76 and 390.66 is: 582.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.83 : 628.76 = 390.66 : x
  2. Step 2: Convert to fraction form
    421.83/628.76 = 390.66/x
  3. Step 3: Cross multiply
    421.83x = 628.76 × 390.66
  4. Step 4: Simplify right side
    421.83x = 245,629.43
  5. Step 5: Solve for x
    x = 245,629.43/421.83
  6. Step 6: Final answer
    x = 582.29

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.