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Finding the Fourth Proportional to 66.20, 91.32 and 39.96

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Solution

The fourth proportional to 66.20, 91.32 and 39.96 is: 55.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.20 : 91.32 = 39.96 : x
  2. Step 2: Convert to fraction form
    66.20/91.32 = 39.96/x
  3. Step 3: Cross multiply
    66.20x = 91.32 × 39.96
  4. Step 4: Simplify right side
    66.20x = 3,649.15
  5. Step 5: Solve for x
    x = 3,649.15/66.20
  6. Step 6: Final answer
    x = 55.12

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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.