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Finding the Fourth Proportional to 31.69, 47.42 and 18.86

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Solution

The fourth proportional to 31.69, 47.42 and 18.86 is: 28.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.69 : 47.42 = 18.86 : x
  2. Step 2: Convert to fraction form
    31.69/47.42 = 18.86/x
  3. Step 3: Cross multiply
    31.69x = 47.42 × 18.86
  4. Step 4: Simplify right side
    31.69x = 894.08
  5. Step 5: Solve for x
    x = 894.08/31.69
  6. Step 6: Final answer
    x = 28.21

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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.