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Finding the Fourth Proportional to 21.58, 29.79 and 12.84

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Solution

The fourth proportional to 21.58, 29.79 and 12.84 is: 17.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.58 : 29.79 = 12.84 : x
  2. Step 2: Convert to fraction form
    21.58/29.79 = 12.84/x
  3. Step 3: Cross multiply
    21.58x = 29.79 × 12.84
  4. Step 4: Simplify right side
    21.58x = 382.44
  5. Step 5: Solve for x
    x = 382.44/21.58
  6. Step 6: Final answer
    x = 17.72

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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.