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Finding the Fourth Proportional to 108.54, 149.78 and 61.90

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Solution

The fourth proportional to 108.54, 149.78 and 61.90 is: 85.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    108.54 : 149.78 = 61.90 : x
  2. Step 2: Convert to fraction form
    108.54/149.78 = 61.90/x
  3. Step 3: Cross multiply
    108.54x = 149.78 × 61.90
  4. Step 4: Simplify right side
    108.54x = 9,271.38
  5. Step 5: Solve for x
    x = 9,271.38/108.54
  6. Step 6: Final answer
    x = 85.42

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.