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Finding the Fourth Proportional to 428.08, 642.30 and 245.20

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Solution

The fourth proportional to 428.08, 642.30 and 245.20 is: 367.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.08 : 642.30 = 245.20 : x
  2. Step 2: Convert to fraction form
    428.08/642.30 = 245.20/x
  3. Step 3: Cross multiply
    428.08x = 642.30 × 245.20
  4. Step 4: Simplify right side
    428.08x = 157,491.96
  5. Step 5: Solve for x
    x = 157,491.96/428.08
  6. Step 6: Final answer
    x = 367.90

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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.