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Finding the Fourth Proportional to 54.21, 81.69 and 45.39

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Solution

The fourth proportional to 54.21, 81.69 and 45.39 is: 68.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    54.21 : 81.69 = 45.39 : x
  2. Step 2: Convert to fraction form
    54.21/81.69 = 45.39/x
  3. Step 3: Cross multiply
    54.21x = 81.69 × 45.39
  4. Step 4: Simplify right side
    54.21x = 3,707.91
  5. Step 5: Solve for x
    x = 3,707.91/54.21
  6. Step 6: Final answer
    x = 68.40

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.