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Finding the Fourth Proportional to 428.80, 643.05 and 209.41

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Solution

The fourth proportional to 428.80, 643.05 and 209.41 is: 314.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.80 : 643.05 = 209.41 : x
  2. Step 2: Convert to fraction form
    428.80/643.05 = 209.41/x
  3. Step 3: Cross multiply
    428.80x = 643.05 × 209.41
  4. Step 4: Simplify right side
    428.80x = 134,661.10
  5. Step 5: Solve for x
    x = 134,661.10/428.80
  6. Step 6: Final answer
    x = 314.04

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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.