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Finding the Fourth Proportional to 13.78, 20.70 and 7.77

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Solution

The fourth proportional to 13.78, 20.70 and 7.77 is: 11.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.78 : 20.70 = 7.77 : x
  2. Step 2: Convert to fraction form
    13.78/20.70 = 7.77/x
  3. Step 3: Cross multiply
    13.78x = 20.70 × 7.77
  4. Step 4: Simplify right side
    13.78x = 160.84
  5. Step 5: Solve for x
    x = 160.84/13.78
  6. Step 6: Final answer
    x = 11.67

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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.