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Finding the Fourth Proportional to 18.78, 25.95 and 15.72

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Solution

The fourth proportional to 18.78, 25.95 and 15.72 is: 21.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.78 : 25.95 = 15.72 : x
  2. Step 2: Convert to fraction form
    18.78/25.95 = 15.72/x
  3. Step 3: Cross multiply
    18.78x = 25.95 × 15.72
  4. Step 4: Simplify right side
    18.78x = 407.93
  5. Step 5: Solve for x
    x = 407.93/18.78
  6. Step 6: Final answer
    x = 21.72

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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.