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Finding the Fourth Proportional to 21.84, 30.15 and 13.68

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Solution

The fourth proportional to 21.84, 30.15 and 13.68 is: 18.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.84 : 30.15 = 13.68 : x
  2. Step 2: Convert to fraction form
    21.84/30.15 = 13.68/x
  3. Step 3: Cross multiply
    21.84x = 30.15 × 13.68
  4. Step 4: Simplify right side
    21.84x = 412.45
  5. Step 5: Solve for x
    x = 412.45/21.84
  6. Step 6: Final answer
    x = 18.89

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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.