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Finding the Fourth Proportional to 208.71, 287.91 and 138.69

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Solution

The fourth proportional to 208.71, 287.91 and 138.69 is: 191.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.71 : 287.91 = 138.69 : x
  2. Step 2: Convert to fraction form
    208.71/287.91 = 138.69/x
  3. Step 3: Cross multiply
    208.71x = 287.91 × 138.69
  4. Step 4: Simplify right side
    208.71x = 39,930.24
  5. Step 5: Solve for x
    x = 39,930.24/208.71
  6. Step 6: Final answer
    x = 191.32

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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.