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Finding the Fourth Proportional to 31.42, 47.16 and 21.28

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Solution

The fourth proportional to 31.42, 47.16 and 21.28 is: 31.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.42 : 47.16 = 21.28 : x
  2. Step 2: Convert to fraction form
    31.42/47.16 = 21.28/x
  3. Step 3: Cross multiply
    31.42x = 47.16 × 21.28
  4. Step 4: Simplify right side
    31.42x = 1,003.56
  5. Step 5: Solve for x
    x = 1,003.56/31.42
  6. Step 6: Final answer
    x = 31.94

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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.