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Finding the Fourth Proportional to 128.70, 176.81 and 120.60

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Solution

The fourth proportional to 128.70, 176.81 and 120.60 is: 165.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.70 : 176.81 = 120.60 : x
  2. Step 2: Convert to fraction form
    128.70/176.81 = 120.60/x
  3. Step 3: Cross multiply
    128.70x = 176.81 × 120.60
  4. Step 4: Simplify right side
    128.70x = 21,322.68
  5. Step 5: Solve for x
    x = 21,322.68/128.70
  6. Step 6: Final answer
    x = 165.68

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.