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Finding the Fourth Proportional to 20.90, 31.47 and 20.75

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Solution

The fourth proportional to 20.90, 31.47 and 20.75 is: 31.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.90 : 31.47 = 20.75 : x
  2. Step 2: Convert to fraction form
    20.90/31.47 = 20.75/x
  3. Step 3: Cross multiply
    20.90x = 31.47 × 20.75
  4. Step 4: Simplify right side
    20.90x = 652.85
  5. Step 5: Solve for x
    x = 652.85/20.90
  6. Step 6: Final answer
    x = 31.24

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.