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Finding the Fourth Proportional to 208.78, 288.14 and 121.43

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Solution

The fourth proportional to 208.78, 288.14 and 121.43 is: 167.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.78 : 288.14 = 121.43 : x
  2. Step 2: Convert to fraction form
    208.78/288.14 = 121.43/x
  3. Step 3: Cross multiply
    208.78x = 288.14 × 121.43
  4. Step 4: Simplify right side
    208.78x = 34,988.95
  5. Step 5: Solve for x
    x = 34,988.95/208.78
  6. Step 6: Final answer
    x = 167.59

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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.