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Finding the Fourth Proportional to 428.65, 642.99 and 140.11

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Solution

The fourth proportional to 428.65, 642.99 and 140.11 is: 210.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.65 : 642.99 = 140.11 : x
  2. Step 2: Convert to fraction form
    428.65/642.99 = 140.11/x
  3. Step 3: Cross multiply
    428.65x = 642.99 × 140.11
  4. Step 4: Simplify right side
    428.65x = 90,086.11
  5. Step 5: Solve for x
    x = 90,086.11/428.65
  6. Step 6: Final answer
    x = 210.16

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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.