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Finding the Fourth Proportional to 421.61, 581.85 and 311.45

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Solution

The fourth proportional to 421.61, 581.85 and 311.45 is: 429.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.61 : 581.85 = 311.45 : x
  2. Step 2: Convert to fraction form
    421.61/581.85 = 311.45/x
  3. Step 3: Cross multiply
    421.61x = 581.85 × 311.45
  4. Step 4: Simplify right side
    421.61x = 181,214.27
  5. Step 5: Solve for x
    x = 181,214.27/421.61
  6. Step 6: Final answer
    x = 429.82

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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.