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Finding the Fourth Proportional to 128.66, 177.60 and 87.27

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Solution

The fourth proportional to 128.66, 177.60 and 87.27 is: 120.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.66 : 177.60 = 87.27 : x
  2. Step 2: Convert to fraction form
    128.66/177.60 = 87.27/x
  3. Step 3: Cross multiply
    128.66x = 177.60 × 87.27
  4. Step 4: Simplify right side
    128.66x = 15,498.49
  5. Step 5: Solve for x
    x = 15,498.49/128.66
  6. Step 6: Final answer
    x = 120.47

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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.