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Finding the Fourth Proportional to 428.50, 643.61 and 255.51

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Solution

The fourth proportional to 428.50, 643.61 and 255.51 is: 383.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.50 : 643.61 = 255.51 : x
  2. Step 2: Convert to fraction form
    428.50/643.61 = 255.51/x
  3. Step 3: Cross multiply
    428.50x = 643.61 × 255.51
  4. Step 4: Simplify right side
    428.50x = 164,446.21
  5. Step 5: Solve for x
    x = 164,446.21/428.50
  6. Step 6: Final answer
    x = 383.77

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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.