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Finding the Fourth Proportional to 428.39, 642.44 and 209.02

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Solution

The fourth proportional to 428.39, 642.44 and 209.02 is: 313.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.39 : 642.44 = 209.02 : x
  2. Step 2: Convert to fraction form
    428.39/642.44 = 209.02/x
  3. Step 3: Cross multiply
    428.39x = 642.44 × 209.02
  4. Step 4: Simplify right side
    428.39x = 134,282.81
  5. Step 5: Solve for x
    x = 134,282.81/428.39
  6. Step 6: Final answer
    x = 313.46

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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.