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Finding the Fourth Proportional to 428.72, 643.16 and 140.16

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Solution

The fourth proportional to 428.72, 643.16 and 140.16 is: 210.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.72 : 643.16 = 140.16 : x
  2. Step 2: Convert to fraction form
    428.72/643.16 = 140.16/x
  3. Step 3: Cross multiply
    428.72x = 643.16 × 140.16
  4. Step 4: Simplify right side
    428.72x = 90,145.31
  5. Step 5: Solve for x
    x = 90,145.31/428.72
  6. Step 6: Final answer
    x = 210.27

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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.