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Finding the Fourth Proportional to 76.90, 105.91 and 66.53

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Solution

The fourth proportional to 76.90, 105.91 and 66.53 is: 91.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.90 : 105.91 = 66.53 : x
  2. Step 2: Convert to fraction form
    76.90/105.91 = 66.53/x
  3. Step 3: Cross multiply
    76.90x = 105.91 × 66.53
  4. Step 4: Simplify right side
    76.90x = 7,046.29
  5. Step 5: Solve for x
    x = 7,046.29/76.90
  6. Step 6: Final answer
    x = 91.63

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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.