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Finding the Fourth Proportional to 86.72, 119.72 and 66

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Solution

The fourth proportional to 86.72, 119.72 and 66 is: 91.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.72 : 119.72 = 66 : x
  2. Step 2: Convert to fraction form
    86.72/119.72 = 66/x
  3. Step 3: Cross multiply
    86.72x = 119.72 × 66
  4. Step 4: Simplify right side
    86.72x = 7,901.52
  5. Step 5: Solve for x
    x = 7,901.52/86.72
  6. Step 6: Final answer
    x = 91.12

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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.