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Finding the Fourth Proportional to 31.14, 42.84 and 30.90

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Solution

The fourth proportional to 31.14, 42.84 and 30.90 is: 42.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.14 : 42.84 = 30.90 : x
  2. Step 2: Convert to fraction form
    31.14/42.84 = 30.90/x
  3. Step 3: Cross multiply
    31.14x = 42.84 × 30.90
  4. Step 4: Simplify right side
    31.14x = 1,323.76
  5. Step 5: Solve for x
    x = 1,323.76/31.14
  6. Step 6: Final answer
    x = 42.51

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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.