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Finding the Fourth Proportional to 22.45, 30.99 and 20.78

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Solution

The fourth proportional to 22.45, 30.99 and 20.78 is: 28.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    22.45 : 30.99 = 20.78 : x
  2. Step 2: Convert to fraction form
    22.45/30.99 = 20.78/x
  3. Step 3: Cross multiply
    22.45x = 30.99 × 20.78
  4. Step 4: Simplify right side
    22.45x = 643.82
  5. Step 5: Solve for x
    x = 643.82/22.45
  6. Step 6: Final answer
    x = 28.68

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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.