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Finding the Fourth Proportional to 31.16, 42.98 and 20.23

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Solution

The fourth proportional to 31.16, 42.98 and 20.23 is: 27.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.16 : 42.98 = 20.23 : x
  2. Step 2: Convert to fraction form
    31.16/42.98 = 20.23/x
  3. Step 3: Cross multiply
    31.16x = 42.98 × 20.23
  4. Step 4: Simplify right side
    31.16x = 869.28
  5. Step 5: Solve for x
    x = 869.28/31.16
  6. Step 6: Final answer
    x = 27.89

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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.