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Finding the Fourth Proportional to 20.61, 30.78 and 18.25

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Solution

The fourth proportional to 20.61, 30.78 and 18.25 is: 27.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.61 : 30.78 = 18.25 : x
  2. Step 2: Convert to fraction form
    20.61/30.78 = 18.25/x
  3. Step 3: Cross multiply
    20.61x = 30.78 × 18.25
  4. Step 4: Simplify right side
    20.61x = 561.66
  5. Step 5: Solve for x
    x = 561.66/20.61
  6. Step 6: Final answer
    x = 27.25

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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.