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Finding the Fourth Proportional to 108.72, 162.78 and 91.36

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Solution

The fourth proportional to 108.72, 162.78 and 91.36 is: 136.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    108.72 : 162.78 = 91.36 : x
  2. Step 2: Convert to fraction form
    108.72/162.78 = 91.36/x
  3. Step 3: Cross multiply
    108.72x = 162.78 × 91.36
  4. Step 4: Simplify right side
    108.72x = 14,871.58
  5. Step 5: Solve for x
    x = 14,871.58/108.72
  6. Step 6: Final answer
    x = 136.79

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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.