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Finding the Fourth Proportional to 77.40, 106.81 and 51.21

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Solution

The fourth proportional to 77.40, 106.81 and 51.21 is: 70.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.40 : 106.81 = 51.21 : x
  2. Step 2: Convert to fraction form
    77.40/106.81 = 51.21/x
  3. Step 3: Cross multiply
    77.40x = 106.81 × 51.21
  4. Step 4: Simplify right side
    77.40x = 5,469.74
  5. Step 5: Solve for x
    x = 5,469.74/77.40
  6. Step 6: Final answer
    x = 70.67

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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.