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Finding the Fourth Proportional to 187.20, 258.72 and 129.12

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Solution

The fourth proportional to 187.20, 258.72 and 129.12 is: 178.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    187.20 : 258.72 = 129.12 : x
  2. Step 2: Convert to fraction form
    187.20/258.72 = 129.12/x
  3. Step 3: Cross multiply
    187.20x = 258.72 × 129.12
  4. Step 4: Simplify right side
    187.20x = 33,405.93
  5. Step 5: Solve for x
    x = 33,405.93/187.20
  6. Step 6: Final answer
    x = 178.45

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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.