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Finding the Fourth Proportional to 21.09, 31.59 and 9.05

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Solution

The fourth proportional to 21.09, 31.59 and 9.05 is: 13.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.09 : 31.59 = 9.05 : x
  2. Step 2: Convert to fraction form
    21.09/31.59 = 9.05/x
  3. Step 3: Cross multiply
    21.09x = 31.59 × 9.05
  4. Step 4: Simplify right side
    21.09x = 285.73
  5. Step 5: Solve for x
    x = 285.73/21.09
  6. Step 6: Final answer
    x = 13.55

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.