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Finding the Fourth Proportional to 2.78, 4.20 and 2.69

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Solution

The fourth proportional to 2.78, 4.20 and 2.69 is: 4.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    2.78 : 4.20 = 2.69 : x
  2. Step 2: Convert to fraction form
    2.78/4.20 = 2.69/x
  3. Step 3: Cross multiply
    2.78x = 4.20 × 2.69
  4. Step 4: Simplify right side
    2.78x = 11.30
  5. Step 5: Solve for x
    x = 11.30/2.78
  6. Step 6: Final answer
    x = 4.06

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.