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Finding the Fourth Proportional to 285.45, 428.18 and 213.81

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Solution

The fourth proportional to 285.45, 428.18 and 213.81 is: 320.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.45 : 428.18 = 213.81 : x
  2. Step 2: Convert to fraction form
    285.45/428.18 = 213.81/x
  3. Step 3: Cross multiply
    285.45x = 428.18 × 213.81
  4. Step 4: Simplify right side
    285.45x = 91,548.10
  5. Step 5: Solve for x
    x = 91,548.10/285.45
  6. Step 6: Final answer
    x = 320.72

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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.