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Finding the Fourth Proportional to 89.72, 123.76 and 78.69

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Solution

The fourth proportional to 89.72, 123.76 and 78.69 is: 108.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.72 : 123.76 = 78.69 : x
  2. Step 2: Convert to fraction form
    89.72/123.76 = 78.69/x
  3. Step 3: Cross multiply
    89.72x = 123.76 × 78.69
  4. Step 4: Simplify right side
    89.72x = 9,738.67
  5. Step 5: Solve for x
    x = 9,738.67/89.72
  6. Step 6: Final answer
    x = 108.55

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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.