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Finding the Fourth Proportional to 20.93, 31.21 and 18.64

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Solution

The fourth proportional to 20.93, 31.21 and 18.64 is: 27.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.93 : 31.21 = 18.64 : x
  2. Step 2: Convert to fraction form
    20.93/31.21 = 18.64/x
  3. Step 3: Cross multiply
    20.93x = 31.21 × 18.64
  4. Step 4: Simplify right side
    20.93x = 581.63
  5. Step 5: Solve for x
    x = 581.63/20.93
  6. Step 6: Final answer
    x = 27.79

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.