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Finding the Fourth Proportional to 108.72, 163.28 and 90.72

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Solution

The fourth proportional to 108.72, 163.28 and 90.72 is: 136.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    108.72 : 163.28 = 90.72 : x
  2. Step 2: Convert to fraction form
    108.72/163.28 = 90.72/x
  3. Step 3: Cross multiply
    108.72x = 163.28 × 90.72
  4. Step 4: Simplify right side
    108.72x = 14,812.76
  5. Step 5: Solve for x
    x = 14,812.76/108.72
  6. Step 6: Final answer
    x = 136.25

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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.