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Finding the Fourth Proportional to 128.97, 178.08 and 79.89

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Solution

The fourth proportional to 128.97, 178.08 and 79.89 is: 110.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.97 : 178.08 = 79.89 : x
  2. Step 2: Convert to fraction form
    128.97/178.08 = 79.89/x
  3. Step 3: Cross multiply
    128.97x = 178.08 × 79.89
  4. Step 4: Simplify right side
    128.97x = 14,226.81
  5. Step 5: Solve for x
    x = 14,226.81/128.97
  6. Step 6: Final answer
    x = 110.31

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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.