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Finding the Fourth Proportional to 21.96, 30.36 and 15.84

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Solution

The fourth proportional to 21.96, 30.36 and 15.84 is: 21.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.96 : 30.36 = 15.84 : x
  2. Step 2: Convert to fraction form
    21.96/30.36 = 15.84/x
  3. Step 3: Cross multiply
    21.96x = 30.36 × 15.84
  4. Step 4: Simplify right side
    21.96x = 480.90
  5. Step 5: Solve for x
    x = 480.90/21.96
  6. Step 6: Final answer
    x = 21.90

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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.