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Finding the Fourth Proportional to 109.20, 163.60 and 66.40

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Solution

The fourth proportional to 109.20, 163.60 and 66.40 is: 99.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    109.20 : 163.60 = 66.40 : x
  2. Step 2: Convert to fraction form
    109.20/163.60 = 66.40/x
  3. Step 3: Cross multiply
    109.20x = 163.60 × 66.40
  4. Step 4: Simplify right side
    109.20x = 10,863.04
  5. Step 5: Solve for x
    x = 10,863.04/109.20
  6. Step 6: Final answer
    x = 99.48

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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.