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Finding the Fourth Proportional to 128.98, 178.02 and 76.56

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Solution

The fourth proportional to 128.98, 178.02 and 76.56 is: 105.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.98 : 178.02 = 76.56 : x
  2. Step 2: Convert to fraction form
    128.98/178.02 = 76.56/x
  3. Step 3: Cross multiply
    128.98x = 178.02 × 76.56
  4. Step 4: Simplify right side
    128.98x = 13,629.21
  5. Step 5: Solve for x
    x = 13,629.21/128.98
  6. Step 6: Final answer
    x = 105.67

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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.