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Finding the Fourth Proportional to 47.21, 65.09 and 30.81

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Solution

The fourth proportional to 47.21, 65.09 and 30.81 is: 42.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.21 : 65.09 = 30.81 : x
  2. Step 2: Convert to fraction form
    47.21/65.09 = 30.81/x
  3. Step 3: Cross multiply
    47.21x = 65.09 × 30.81
  4. Step 4: Simplify right side
    47.21x = 2,005.42
  5. Step 5: Solve for x
    x = 2,005.42/47.21
  6. Step 6: Final answer
    x = 42.48

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.