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Finding the Fourth Proportional to 2.81, 4.21 and 2.09

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Solution

The fourth proportional to 2.81, 4.21 and 2.09 is: 3.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    2.81 : 4.21 = 2.09 : x
  2. Step 2: Convert to fraction form
    2.81/4.21 = 2.09/x
  3. Step 3: Cross multiply
    2.81x = 4.21 × 2.09
  4. Step 4: Simplify right side
    2.81x = 8.81
  5. Step 5: Solve for x
    x = 8.81/2.81
  6. Step 6: Final answer
    x = 3.13

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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.