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Finding the Fourth Proportional to 66.21, 99.31 and 20.56

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Solution

The fourth proportional to 66.21, 99.31 and 20.56 is: 30.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.21 : 99.31 = 20.56 : x
  2. Step 2: Convert to fraction form
    66.21/99.31 = 20.56/x
  3. Step 3: Cross multiply
    66.21x = 99.31 × 20.56
  4. Step 4: Simplify right side
    66.21x = 2,041.81
  5. Step 5: Solve for x
    x = 2,041.81/66.21
  6. Step 6: Final answer
    x = 30.84

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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.