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Finding the Fourth Proportional to 428.04, 639.56 and 345.80

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Solution

The fourth proportional to 428.04, 639.56 and 345.80 is: 516.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.04 : 639.56 = 345.80 : x
  2. Step 2: Convert to fraction form
    428.04/639.56 = 345.80/x
  3. Step 3: Cross multiply
    428.04x = 639.56 × 345.80
  4. Step 4: Simplify right side
    428.04x = 221,159.85
  5. Step 5: Solve for x
    x = 221,159.85/428.04
  6. Step 6: Final answer
    x = 516.68

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.