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Finding the Fourth Proportional to 128.80, 192.47 and 92.80

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Solution

The fourth proportional to 128.80, 192.47 and 92.80 is: 138.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.80 : 192.47 = 92.80 : x
  2. Step 2: Convert to fraction form
    128.80/192.47 = 92.80/x
  3. Step 3: Cross multiply
    128.80x = 192.47 × 92.80
  4. Step 4: Simplify right side
    128.80x = 17,861.22
  5. Step 5: Solve for x
    x = 17,861.22/128.80
  6. Step 6: Final answer
    x = 138.67

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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.