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Finding the Fourth Proportional to 208.59, 287.97 and 138.70

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Solution

The fourth proportional to 208.59, 287.97 and 138.70 is: 191.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.59 : 287.97 = 138.70 : x
  2. Step 2: Convert to fraction form
    208.59/287.97 = 138.70/x
  3. Step 3: Cross multiply
    208.59x = 287.97 × 138.70
  4. Step 4: Simplify right side
    208.59x = 39,942.87
  5. Step 5: Solve for x
    x = 39,942.87/208.59
  6. Step 6: Final answer
    x = 191.49

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.