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Finding the Fourth Proportional to 427.50, 641.43 and 139.05

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Solution

The fourth proportional to 427.50, 641.43 and 139.05 is: 208.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.50 : 641.43 = 139.05 : x
  2. Step 2: Convert to fraction form
    427.50/641.43 = 139.05/x
  3. Step 3: Cross multiply
    427.50x = 641.43 × 139.05
  4. Step 4: Simplify right side
    427.50x = 89,190.84
  5. Step 5: Solve for x
    x = 89,190.84/427.50
  6. Step 6: Final answer
    x = 208.63

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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.