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Finding the Fourth Proportional to 66.20, 91.31 and 47.75

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Solution

The fourth proportional to 66.20, 91.31 and 47.75 is: 65.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.20 : 91.31 = 47.75 : x
  2. Step 2: Convert to fraction form
    66.20/91.31 = 47.75/x
  3. Step 3: Cross multiply
    66.20x = 91.31 × 47.75
  4. Step 4: Simplify right side
    66.20x = 4,359.36
  5. Step 5: Solve for x
    x = 4,359.36/66.20
  6. Step 6: Final answer
    x = 65.86

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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.