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Finding the Fourth Proportional to 76.86, 105.77 and 66.47

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Solution

The fourth proportional to 76.86, 105.77 and 66.47 is: 91.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.86 : 105.77 = 66.47 : x
  2. Step 2: Convert to fraction form
    76.86/105.77 = 66.47/x
  3. Step 3: Cross multiply
    76.86x = 105.77 × 66.47
  4. Step 4: Simplify right side
    76.86x = 7,029.67
  5. Step 5: Solve for x
    x = 7,029.67/76.86
  6. Step 6: Final answer
    x = 91.46

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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.