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Finding the Fourth Proportional to 103.86, 155.64 and 78.05

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Solution

The fourth proportional to 103.86, 155.64 and 78.05 is: 116.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.86 : 155.64 = 78.05 : x
  2. Step 2: Convert to fraction form
    103.86/155.64 = 78.05/x
  3. Step 3: Cross multiply
    103.86x = 155.64 × 78.05
  4. Step 4: Simplify right side
    103.86x = 12,146.92
  5. Step 5: Solve for x
    x = 12,146.92/103.86
  6. Step 6: Final answer
    x = 116.95

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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.