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Finding the Fourth Proportional to 421.85, 582.31 and 312.21

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Solution

The fourth proportional to 421.85, 582.31 and 312.21 is: 430.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.85 : 582.31 = 312.21 : x
  2. Step 2: Convert to fraction form
    421.85/582.31 = 312.21/x
  3. Step 3: Cross multiply
    421.85x = 582.31 × 312.21
  4. Step 4: Simplify right side
    421.85x = 181,800.09
  5. Step 5: Solve for x
    x = 181,800.09/421.85
  6. Step 6: Final answer
    x = 430.96

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.