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Finding the Fourth Proportional to 30.50, 42.09 and 21.89

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Solution

The fourth proportional to 30.50, 42.09 and 21.89 is: 30.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.50 : 42.09 = 21.89 : x
  2. Step 2: Convert to fraction form
    30.50/42.09 = 21.89/x
  3. Step 3: Cross multiply
    30.50x = 42.09 × 21.89
  4. Step 4: Simplify right side
    30.50x = 921.35
  5. Step 5: Solve for x
    x = 921.35/30.50
  6. Step 6: Final answer
    x = 30.21

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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.