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Finding the Fourth Proportional to 27.21, 40.80 and 12.78

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Solution

The fourth proportional to 27.21, 40.80 and 12.78 is: 19.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    27.21 : 40.80 = 12.78 : x
  2. Step 2: Convert to fraction form
    27.21/40.80 = 12.78/x
  3. Step 3: Cross multiply
    27.21x = 40.80 × 12.78
  4. Step 4: Simplify right side
    27.21x = 521.42
  5. Step 5: Solve for x
    x = 521.42/27.21
  6. Step 6: Final answer
    x = 19.16

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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.