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Finding the Fourth Proportional to 30.73, 42.40 and 21.55

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Solution

The fourth proportional to 30.73, 42.40 and 21.55 is: 29.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.73 : 42.40 = 21.55 : x
  2. Step 2: Convert to fraction form
    30.73/42.40 = 21.55/x
  3. Step 3: Cross multiply
    30.73x = 42.40 × 21.55
  4. Step 4: Simplify right side
    30.73x = 913.72
  5. Step 5: Solve for x
    x = 913.72/30.73
  6. Step 6: Final answer
    x = 29.73

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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.