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Finding the Fourth Proportional to 119.50, 178.90 and 78.90

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Solution

The fourth proportional to 119.50, 178.90 and 78.90 is: 118.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    119.50 : 178.90 = 78.90 : x
  2. Step 2: Convert to fraction form
    119.50/178.90 = 78.90/x
  3. Step 3: Cross multiply
    119.50x = 178.90 × 78.90
  4. Step 4: Simplify right side
    119.50x = 14,115.21
  5. Step 5: Solve for x
    x = 14,115.21/119.50
  6. Step 6: Final answer
    x = 118.12

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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.