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Finding the Fourth Proportional to 109.42, 163.86 and 86.41

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Solution

The fourth proportional to 109.42, 163.86 and 86.41 is: 129.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    109.42 : 163.86 = 86.41 : x
  2. Step 2: Convert to fraction form
    109.42/163.86 = 86.41/x
  3. Step 3: Cross multiply
    109.42x = 163.86 × 86.41
  4. Step 4: Simplify right side
    109.42x = 14,159.14
  5. Step 5: Solve for x
    x = 14,159.14/109.42
  6. Step 6: Final answer
    x = 129.40

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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.