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Finding the Fourth Proportional to 30.78, 46.17 and 21.15

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Solution

The fourth proportional to 30.78, 46.17 and 21.15 is: 31.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.78 : 46.17 = 21.15 : x
  2. Step 2: Convert to fraction form
    30.78/46.17 = 21.15/x
  3. Step 3: Cross multiply
    30.78x = 46.17 × 21.15
  4. Step 4: Simplify right side
    30.78x = 976.50
  5. Step 5: Solve for x
    x = 976.50/30.78
  6. Step 6: Final answer
    x = 31.73

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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.