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Finding the Fourth Proportional to 66.81, 100.18 and 21.15

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Solution

The fourth proportional to 66.81, 100.18 and 21.15 is: 31.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.81 : 100.18 = 21.15 : x
  2. Step 2: Convert to fraction form
    66.81/100.18 = 21.15/x
  3. Step 3: Cross multiply
    66.81x = 100.18 × 21.15
  4. Step 4: Simplify right side
    66.81x = 2,118.81
  5. Step 5: Solve for x
    x = 2,118.81/66.81
  6. Step 6: Final answer
    x = 31.71

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.