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Finding the Fourth Proportional to 47.72, 65.78 and 31.31

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Solution

The fourth proportional to 47.72, 65.78 and 31.31 is: 43.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.72 : 65.78 = 31.31 : x
  2. Step 2: Convert to fraction form
    47.72/65.78 = 31.31/x
  3. Step 3: Cross multiply
    47.72x = 65.78 × 31.31
  4. Step 4: Simplify right side
    47.72x = 2,059.57
  5. Step 5: Solve for x
    x = 2,059.57/47.72
  6. Step 6: Final answer
    x = 43.16

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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.