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Finding the Fourth Proportional to 208.66, 288 and 138.72

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Solution

The fourth proportional to 208.66, 288 and 138.72 is: 191.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.66 : 288 = 138.72 : x
  2. Step 2: Convert to fraction form
    208.66/288 = 138.72/x
  3. Step 3: Cross multiply
    208.66x = 288 × 138.72
  4. Step 4: Simplify right side
    208.66x = 39,951.36
  5. Step 5: Solve for x
    x = 39,951.36/208.66
  6. Step 6: Final answer
    x = 191.47

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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.