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Finding the Fourth Proportional to 31.61, 47.42 and 8.79

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Solution

The fourth proportional to 31.61, 47.42 and 8.79 is: 13.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.61 : 47.42 = 8.79 : x
  2. Step 2: Convert to fraction form
    31.61/47.42 = 8.79/x
  3. Step 3: Cross multiply
    31.61x = 47.42 × 8.79
  4. Step 4: Simplify right side
    31.61x = 416.55
  5. Step 5: Solve for x
    x = 416.55/31.61
  6. Step 6: Final answer
    x = 13.18

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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.