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Finding the Fourth Proportional to 428.95, 643.53 and 140.39

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Solution

The fourth proportional to 428.95, 643.53 and 140.39 is: 210.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.95 : 643.53 = 140.39 : x
  2. Step 2: Convert to fraction form
    428.95/643.53 = 140.39/x
  3. Step 3: Cross multiply
    428.95x = 643.53 × 140.39
  4. Step 4: Simplify right side
    428.95x = 90,345.18
  5. Step 5: Solve for x
    x = 90,345.18/428.95
  6. Step 6: Final answer
    x = 210.62

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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.