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Finding the Fourth Proportional to 208.51, 287.80 and 129.78

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Solution

The fourth proportional to 208.51, 287.80 and 129.78 is: 179.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.51 : 287.80 = 129.78 : x
  2. Step 2: Convert to fraction form
    208.51/287.80 = 129.78/x
  3. Step 3: Cross multiply
    208.51x = 287.80 × 129.78
  4. Step 4: Simplify right side
    208.51x = 37,351.03
  5. Step 5: Solve for x
    x = 37,351.03/208.51
  6. Step 6: Final answer
    x = 179.14

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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.