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Finding the Fourth Proportional to 21.23, 31.78 and 12.19

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Solution

The fourth proportional to 21.23, 31.78 and 12.19 is: 18.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.23 : 31.78 = 12.19 : x
  2. Step 2: Convert to fraction form
    21.23/31.78 = 12.19/x
  3. Step 3: Cross multiply
    21.23x = 31.78 × 12.19
  4. Step 4: Simplify right side
    21.23x = 387.40
  5. Step 5: Solve for x
    x = 387.40/21.23
  6. Step 6: Final answer
    x = 18.25

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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.