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Finding the Fourth Proportional to 31.28, 46.85 and 13.20

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Solution

The fourth proportional to 31.28, 46.85 and 13.20 is: 19.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.28 : 46.85 = 13.20 : x
  2. Step 2: Convert to fraction form
    31.28/46.85 = 13.20/x
  3. Step 3: Cross multiply
    31.28x = 46.85 × 13.20
  4. Step 4: Simplify right side
    31.28x = 618.35
  5. Step 5: Solve for x
    x = 618.35/31.28
  6. Step 6: Final answer
    x = 19.77

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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.