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Finding the Fourth Proportional to 77.42, 106.90 and 51.21

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Solution

The fourth proportional to 77.42, 106.90 and 51.21 is: 70.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.42 : 106.90 = 51.21 : x
  2. Step 2: Convert to fraction form
    77.42/106.90 = 51.21/x
  3. Step 3: Cross multiply
    77.42x = 106.90 × 51.21
  4. Step 4: Simplify right side
    77.42x = 5,474.35
  5. Step 5: Solve for x
    x = 5,474.35/77.42
  6. Step 6: Final answer
    x = 70.71

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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.