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Finding the Fourth Proportional to 208.65, 287.88 and 138.75

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Solution

The fourth proportional to 208.65, 287.88 and 138.75 is: 191.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.65 : 287.88 = 138.75 : x
  2. Step 2: Convert to fraction form
    208.65/287.88 = 138.75/x
  3. Step 3: Cross multiply
    208.65x = 287.88 × 138.75
  4. Step 4: Simplify right side
    208.65x = 39,943.35
  5. Step 5: Solve for x
    x = 39,943.35/208.65
  6. Step 6: Final answer
    x = 191.44

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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.