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Finding the Fourth Proportional to 428, 641.72 and 171.28

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Solution

The fourth proportional to 428, 641.72 and 171.28 is: 256.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    428 : 641.72 = 171.28 : x
  2. Step 2: Convert to fraction form
    428/641.72 = 171.28/x
  3. Step 3: Cross multiply
    428x = 641.72 × 171.28
  4. Step 4: Simplify right side
    428x = 109,913.80
  5. Step 5: Solve for x
    x = 109,913.80/428
  6. Step 6: Final answer
    x = 256.81

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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.