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Finding the Fourth Proportional to 97.80, 146.90 and 86.05

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Solution

The fourth proportional to 97.80, 146.90 and 86.05 is: 129.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    97.80 : 146.90 = 86.05 : x
  2. Step 2: Convert to fraction form
    97.80/146.90 = 86.05/x
  3. Step 3: Cross multiply
    97.80x = 146.90 × 86.05
  4. Step 4: Simplify right side
    97.80x = 12,640.75
  5. Step 5: Solve for x
    x = 12,640.75/97.80
  6. Step 6: Final answer
    x = 129.25

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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.