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Finding the Fourth Proportional to 42.74, 64.13 and 21.09

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Solution

The fourth proportional to 42.74, 64.13 and 21.09 is: 31.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.74 : 64.13 = 21.09 : x
  2. Step 2: Convert to fraction form
    42.74/64.13 = 21.09/x
  3. Step 3: Cross multiply
    42.74x = 64.13 × 21.09
  4. Step 4: Simplify right side
    42.74x = 1,352.72
  5. Step 5: Solve for x
    x = 1,352.72/42.74
  6. Step 6: Final answer
    x = 31.65

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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.