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Finding the Fourth Proportional to 81.80, 112.71 and 66.20

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Solution

The fourth proportional to 81.80, 112.71 and 66.20 is: 91.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.80 : 112.71 = 66.20 : x
  2. Step 2: Convert to fraction form
    81.80/112.71 = 66.20/x
  3. Step 3: Cross multiply
    81.80x = 112.71 × 66.20
  4. Step 4: Simplify right side
    81.80x = 7,461.93
  5. Step 5: Solve for x
    x = 7,461.93/81.80
  6. Step 6: Final answer
    x = 91.23

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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.