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Finding the Fourth Proportional to 31.30, 43.20 and 20.95

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Solution

The fourth proportional to 31.30, 43.20 and 20.95 is: 28.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.30 : 43.20 = 20.95 : x
  2. Step 2: Convert to fraction form
    31.30/43.20 = 20.95/x
  3. Step 3: Cross multiply
    31.30x = 43.20 × 20.95
  4. Step 4: Simplify right side
    31.30x = 904.93
  5. Step 5: Solve for x
    x = 904.93/31.30
  6. Step 6: Final answer
    x = 28.91

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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.