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Finding the Fourth Proportional to 128.45, 192.48 and 89.80

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Solution

The fourth proportional to 128.45, 192.48 and 89.80 is: 134.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.45 : 192.48 = 89.80 : x
  2. Step 2: Convert to fraction form
    128.45/192.48 = 89.80/x
  3. Step 3: Cross multiply
    128.45x = 192.48 × 89.80
  4. Step 4: Simplify right side
    128.45x = 17,283.74
  5. Step 5: Solve for x
    x = 17,283.74/128.45
  6. Step 6: Final answer
    x = 134.56

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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.