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Finding the Fourth Proportional to 21.78, 29.98 and 20.76

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Solution

The fourth proportional to 21.78, 29.98 and 20.76 is: 28.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.78 : 29.98 = 20.76 : x
  2. Step 2: Convert to fraction form
    21.78/29.98 = 20.76/x
  3. Step 3: Cross multiply
    21.78x = 29.98 × 20.76
  4. Step 4: Simplify right side
    21.78x = 622.38
  5. Step 5: Solve for x
    x = 622.38/21.78
  6. Step 6: Final answer
    x = 28.58

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1.5x scale

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.