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Finding the Fourth Proportional to 109.20, 163.72 and 78.37

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Solution

The fourth proportional to 109.20, 163.72 and 78.37 is: 117.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    109.20 : 163.72 = 78.37 : x
  2. Step 2: Convert to fraction form
    109.20/163.72 = 78.37/x
  3. Step 3: Cross multiply
    109.20x = 163.72 × 78.37
  4. Step 4: Simplify right side
    109.20x = 12,830.43
  5. Step 5: Solve for x
    x = 12,830.43/109.20
  6. Step 6: Final answer
    x = 117.50

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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.