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Finding the Fourth Proportional to 76.75, 105.65 and 66.78

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Solution

The fourth proportional to 76.75, 105.65 and 66.78 is: 91.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.75 : 105.65 = 66.78 : x
  2. Step 2: Convert to fraction form
    76.75/105.65 = 66.78/x
  3. Step 3: Cross multiply
    76.75x = 105.65 × 66.78
  4. Step 4: Simplify right side
    76.75x = 7,055.31
  5. Step 5: Solve for x
    x = 7,055.31/76.75
  6. Step 6: Final answer
    x = 91.93

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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.