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Finding the Fourth Proportional to 427.84, 641.72 and 139.28

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Solution

The fourth proportional to 427.84, 641.72 and 139.28 is: 208.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.84 : 641.72 = 139.28 : x
  2. Step 2: Convert to fraction form
    427.84/641.72 = 139.28/x
  3. Step 3: Cross multiply
    427.84x = 641.72 × 139.28
  4. Step 4: Simplify right side
    427.84x = 89,378.76
  5. Step 5: Solve for x
    x = 89,378.76/427.84
  6. Step 6: Final answer
    x = 208.91

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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.