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Finding the Fourth Proportional to 7.86, 11.78 and 5.20

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Solution

The fourth proportional to 7.86, 11.78 and 5.20 is: 7.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    7.86 : 11.78 = 5.20 : x
  2. Step 2: Convert to fraction form
    7.86/11.78 = 5.20/x
  3. Step 3: Cross multiply
    7.86x = 11.78 × 5.20
  4. Step 4: Simplify right side
    7.86x = 61.26
  5. Step 5: Solve for x
    x = 61.26/7.86
  6. Step 6: Final answer
    x = 7.79

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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.