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Finding the Fourth Proportional to 109.35, 163.72 and 78.67

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Solution

The fourth proportional to 109.35, 163.72 and 78.67 is: 117.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    109.35 : 163.72 = 78.67 : x
  2. Step 2: Convert to fraction form
    109.35/163.72 = 78.67/x
  3. Step 3: Cross multiply
    109.35x = 163.72 × 78.67
  4. Step 4: Simplify right side
    109.35x = 12,880.16
  5. Step 5: Solve for x
    x = 12,880.16/109.35
  6. Step 6: Final answer
    x = 117.79

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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.