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Finding the Fourth Proportional to 428.52, 642.78 and 256.38

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Solution

The fourth proportional to 428.52, 642.78 and 256.38 is: 384.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.52 : 642.78 = 256.38 : x
  2. Step 2: Convert to fraction form
    428.52/642.78 = 256.38/x
  3. Step 3: Cross multiply
    428.52x = 642.78 × 256.38
  4. Step 4: Simplify right side
    428.52x = 164,795.94
  5. Step 5: Solve for x
    x = 164,795.94/428.52
  6. Step 6: Final answer
    x = 384.57

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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.