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Finding the Fourth Proportional to 2.78, 3.84 and 2.21

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Solution

The fourth proportional to 2.78, 3.84 and 2.21 is: 3.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    2.78 : 3.84 = 2.21 : x
  2. Step 2: Convert to fraction form
    2.78/3.84 = 2.21/x
  3. Step 3: Cross multiply
    2.78x = 3.84 × 2.21
  4. Step 4: Simplify right side
    2.78x = 8.46
  5. Step 5: Solve for x
    x = 8.46/2.78
  6. Step 6: Final answer
    x = 3.05

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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.