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Finding the Fourth Proportional to 208.72, 288.05 and 138.65

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Solution

The fourth proportional to 208.72, 288.05 and 138.65 is: 191.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.72 : 288.05 = 138.65 : x
  2. Step 2: Convert to fraction form
    208.72/288.05 = 138.65/x
  3. Step 3: Cross multiply
    208.72x = 288.05 × 138.65
  4. Step 4: Simplify right side
    208.72x = 39,937.44
  5. Step 5: Solve for x
    x = 39,937.44/208.72
  6. Step 6: Final answer
    x = 191.35

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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.