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Finding the Fourth Proportional to 31.21, 43.08 and 30.21

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Solution

The fourth proportional to 31.21, 43.08 and 30.21 is: 41.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.21 : 43.08 = 30.21 : x
  2. Step 2: Convert to fraction form
    31.21/43.08 = 30.21/x
  3. Step 3: Cross multiply
    31.21x = 43.08 × 30.21
  4. Step 4: Simplify right side
    31.21x = 1,301.45
  5. Step 5: Solve for x
    x = 1,301.45/31.21
  6. Step 6: Final answer
    x = 41.70

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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.