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Finding the Fourth Proportional to 428.39, 642.71 and 209.00

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Solution

The fourth proportional to 428.39, 642.71 and 209.00 is: 313.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.39 : 642.71 = 209.00 : x
  2. Step 2: Convert to fraction form
    428.39/642.71 = 209.00/x
  3. Step 3: Cross multiply
    428.39x = 642.71 × 209.00
  4. Step 4: Simplify right side
    428.39x = 134,328.52
  5. Step 5: Solve for x
    x = 134,328.52/428.39
  6. Step 6: Final answer
    x = 313.57

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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.