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Finding the Fourth Proportional to 128.58, 177.45 and 120.77

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Solution

The fourth proportional to 128.58, 177.45 and 120.77 is: 166.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.58 : 177.45 = 120.77 : x
  2. Step 2: Convert to fraction form
    128.58/177.45 = 120.77/x
  3. Step 3: Cross multiply
    128.58x = 177.45 × 120.77
  4. Step 4: Simplify right side
    128.58x = 21,429.75
  5. Step 5: Solve for x
    x = 21,429.75/128.58
  6. Step 6: Final answer
    x = 166.66

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.