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Finding the Fourth Proportional to 79.72, 109.90 and 66.63

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Solution

The fourth proportional to 79.72, 109.90 and 66.63 is: 91.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.72 : 109.90 = 66.63 : x
  2. Step 2: Convert to fraction form
    79.72/109.90 = 66.63/x
  3. Step 3: Cross multiply
    79.72x = 109.90 × 66.63
  4. Step 4: Simplify right side
    79.72x = 7,322.64
  5. Step 5: Solve for x
    x = 7,322.64/79.72
  6. Step 6: Final answer
    x = 91.85

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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.