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Finding the Fourth Proportional to 128.49, 178.37 and 120.39

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Solution

The fourth proportional to 128.49, 178.37 and 120.39 is: 167.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.49 : 178.37 = 120.39 : x
  2. Step 2: Convert to fraction form
    128.49/178.37 = 120.39/x
  3. Step 3: Cross multiply
    128.49x = 178.37 × 120.39
  4. Step 4: Simplify right side
    128.49x = 21,473.81
  5. Step 5: Solve for x
    x = 21,473.81/128.49
  6. Step 6: Final answer
    x = 167.12

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.