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Finding the Fourth Proportional to 428.72, 643.02 and 185.40

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Solution

The fourth proportional to 428.72, 643.02 and 185.40 is: 278.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.72 : 643.02 = 185.40 : x
  2. Step 2: Convert to fraction form
    428.72/643.02 = 185.40/x
  3. Step 3: Cross multiply
    428.72x = 643.02 × 185.40
  4. Step 4: Simplify right side
    428.72x = 119,215.91
  5. Step 5: Solve for x
    x = 119,215.91/428.72
  6. Step 6: Final answer
    x = 278.08

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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.