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Finding the Fourth Proportional to 208, 287.28 and 138.88

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Solution

The fourth proportional to 208, 287.28 and 138.88 is: 191.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    208 : 287.28 = 138.88 : x
  2. Step 2: Convert to fraction form
    208/287.28 = 138.88/x
  3. Step 3: Cross multiply
    208x = 287.28 × 138.88
  4. Step 4: Simplify right side
    208x = 39,897.45
  5. Step 5: Solve for x
    x = 39,897.45/208
  6. Step 6: Final answer
    x = 191.81

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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.