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Finding the Fourth Proportional to 31.75, 47.80 and 28.39

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Solution

The fourth proportional to 31.75, 47.80 and 28.39 is: 42.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.75 : 47.80 = 28.39 : x
  2. Step 2: Convert to fraction form
    31.75/47.80 = 28.39/x
  3. Step 3: Cross multiply
    31.75x = 47.80 × 28.39
  4. Step 4: Simplify right side
    31.75x = 1,357.04
  5. Step 5: Solve for x
    x = 1,357.04/31.75
  6. Step 6: Final answer
    x = 42.74

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.