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Finding the Fourth Proportional to 92.80, 138.48 and 85.80

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Solution

The fourth proportional to 92.80, 138.48 and 85.80 is: 128.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    92.80 : 138.48 = 85.80 : x
  2. Step 2: Convert to fraction form
    92.80/138.48 = 85.80/x
  3. Step 3: Cross multiply
    92.80x = 138.48 × 85.80
  4. Step 4: Simplify right side
    92.80x = 11,881.58
  5. Step 5: Solve for x
    x = 11,881.58/92.80
  6. Step 6: Final answer
    x = 128.03

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.