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Finding the Fourth Proportional to 72.78, 109.16 and 21.44

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Solution

The fourth proportional to 72.78, 109.16 and 21.44 is: 32.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.78 : 109.16 = 21.44 : x
  2. Step 2: Convert to fraction form
    72.78/109.16 = 21.44/x
  3. Step 3: Cross multiply
    72.78x = 109.16 × 21.44
  4. Step 4: Simplify right side
    72.78x = 2,340.39
  5. Step 5: Solve for x
    x = 2,340.39/72.78
  6. Step 6: Final answer
    x = 32.16

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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.