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Finding the Fourth Proportional to 86.38, 119.09 and 61.78

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Solution

The fourth proportional to 86.38, 119.09 and 61.78 is: 85.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.38 : 119.09 = 61.78 : x
  2. Step 2: Convert to fraction form
    86.38/119.09 = 61.78/x
  3. Step 3: Cross multiply
    86.38x = 119.09 × 61.78
  4. Step 4: Simplify right side
    86.38x = 7,357.53
  5. Step 5: Solve for x
    x = 7,357.53/86.38
  6. Step 6: Final answer
    x = 85.17

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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.