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Finding the Fourth Proportional to 21.09, 31.64 and 18.79

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Solution

The fourth proportional to 21.09, 31.64 and 18.79 is: 28.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.09 : 31.64 = 18.79 : x
  2. Step 2: Convert to fraction form
    21.09/31.64 = 18.79/x
  3. Step 3: Cross multiply
    21.09x = 31.64 × 18.79
  4. Step 4: Simplify right side
    21.09x = 594.48
  5. Step 5: Solve for x
    x = 594.48/21.09
  6. Step 6: Final answer
    x = 28.19

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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.