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Finding the Fourth Proportional to 3.91, 5.40 and 3.78

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Solution

The fourth proportional to 3.91, 5.40 and 3.78 is: 5.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    3.91 : 5.40 = 3.78 : x
  2. Step 2: Convert to fraction form
    3.91/5.40 = 3.78/x
  3. Step 3: Cross multiply
    3.91x = 5.40 × 3.78
  4. Step 4: Simplify right side
    3.91x = 20.41
  5. Step 5: Solve for x
    x = 20.41/3.91
  6. Step 6: Final answer
    x = 5.22

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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.