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Finding the Fourth Proportional to 15.15, 21.78 and 15.15

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Solution

The fourth proportional to 15.15, 21.78 and 15.15 is: 21.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.15 : 21.78 = 15.15 : x
  2. Step 2: Convert to fraction form
    15.15/21.78 = 15.15/x
  3. Step 3: Cross multiply
    15.15x = 21.78 × 15.15
  4. Step 4: Simplify right side
    15.15x = 329.97
  5. Step 5: Solve for x
    x = 329.97/15.15
  6. Step 6: Final answer
    x = 21.78

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Why These Related Problems?

These problems maintain the same ratio (1.44) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.