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Finding the Fourth Proportional to 98.75, 136.28 and 61.90

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Solution

The fourth proportional to 98.75, 136.28 and 61.90 is: 85.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.75 : 136.28 = 61.90 : x
  2. Step 2: Convert to fraction form
    98.75/136.28 = 61.90/x
  3. Step 3: Cross multiply
    98.75x = 136.28 × 61.90
  4. Step 4: Simplify right side
    98.75x = 8,435.55
  5. Step 5: Solve for x
    x = 8,435.55/98.75
  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.