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Finding the Fourth Proportional to 119.40, 178.82 and 78.72

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Solution

The fourth proportional to 119.40, 178.82 and 78.72 is: 117.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    119.40 : 178.82 = 78.72 : x
  2. Step 2: Convert to fraction form
    119.40/178.82 = 78.72/x
  3. Step 3: Cross multiply
    119.40x = 178.82 × 78.72
  4. Step 4: Simplify right side
    119.40x = 14,076.71
  5. Step 5: Solve for x
    x = 14,076.71/119.40
  6. Step 6: Final answer
    x = 117.90

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.