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Finding the Fourth Proportional to 187.31, 258.49 and 121.80

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Solution

The fourth proportional to 187.31, 258.49 and 121.80 is: 168.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    187.31 : 258.49 = 121.80 : x
  2. Step 2: Convert to fraction form
    187.31/258.49 = 121.80/x
  3. Step 3: Cross multiply
    187.31x = 258.49 × 121.80
  4. Step 4: Simplify right side
    187.31x = 31,485.20
  5. Step 5: Solve for x
    x = 31,485.20/187.31
  6. Step 6: Final answer
    x = 168.09

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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.