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Finding the Fourth Proportional to 0.81, 1.21 and 0.31

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Solution

The fourth proportional to 0.81, 1.21 and 0.31 is: 0.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    0.81 : 1.21 = 0.31 : x
  2. Step 2: Convert to fraction form
    0.81/1.21 = 0.31/x
  3. Step 3: Cross multiply
    0.81x = 1.21 × 0.31
  4. Step 4: Simplify right side
    0.81x = 0.37
  5. Step 5: Solve for x
    x = 0.37/0.81
  6. Step 6: Final answer
    x = 0.46

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.