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Finding the Fourth Proportional to 15.72, 21.79 and 15.22

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Solution

The fourth proportional to 15.72, 21.79 and 15.22 is: 21.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.72 : 21.79 = 15.22 : x
  2. Step 2: Convert to fraction form
    15.72/21.79 = 15.22/x
  3. Step 3: Cross multiply
    15.72x = 21.79 × 15.22
  4. Step 4: Simplify right side
    15.72x = 331.64
  5. Step 5: Solve for x
    x = 331.64/15.72
  6. Step 6: Final answer
    x = 21.10

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.