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Finding the Fourth Proportional to 86.61, 119.31 and 72.79

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Solution

The fourth proportional to 86.61, 119.31 and 72.79 is: 100.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.61 : 119.31 = 72.79 : x
  2. Step 2: Convert to fraction form
    86.61/119.31 = 72.79/x
  3. Step 3: Cross multiply
    86.61x = 119.31 × 72.79
  4. Step 4: Simplify right side
    86.61x = 8,684.57
  5. Step 5: Solve for x
    x = 8,684.57/86.61
  6. Step 6: Final answer
    x = 100.27

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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.