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Finding the Fourth Proportional to 3.90, 5.85 and 2.21

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Solution

The fourth proportional to 3.90, 5.85 and 2.21 is: 3.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    3.90 : 5.85 = 2.21 : x
  2. Step 2: Convert to fraction form
    3.90/5.85 = 2.21/x
  3. Step 3: Cross multiply
    3.90x = 5.85 × 2.21
  4. Step 4: Simplify right side
    3.90x = 12.90
  5. Step 5: Solve for x
    x = 12.90/3.90
  6. Step 6: Final answer
    x = 3.31

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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.