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Finding the Fourth Proportional to 122.21, 168.64 and 78.50

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Solution

The fourth proportional to 122.21, 168.64 and 78.50 is: 108.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.21 : 168.64 = 78.50 : x
  2. Step 2: Convert to fraction form
    122.21/168.64 = 78.50/x
  3. Step 3: Cross multiply
    122.21x = 168.64 × 78.50
  4. Step 4: Simplify right side
    122.21x = 13,238.24
  5. Step 5: Solve for x
    x = 13,238.24/122.21
  6. Step 6: Final answer
    x = 108.32

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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.