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Finding the Fourth Proportional to 108.78, 163.20 and 66

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Solution

The fourth proportional to 108.78, 163.20 and 66 is: 99.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    108.78 : 163.20 = 66 : x
  2. Step 2: Convert to fraction form
    108.78/163.20 = 66/x
  3. Step 3: Cross multiply
    108.78x = 163.20 × 66
  4. Step 4: Simplify right side
    108.78x = 10,771.20
  5. Step 5: Solve for x
    x = 10,771.20/108.78
  6. Step 6: Final answer
    x = 99.02

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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.