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Finding the Fourth Proportional to 78.85, 108.94 and 72.77

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Solution

The fourth proportional to 78.85, 108.94 and 72.77 is: 100.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.85 : 108.94 = 72.77 : x
  2. Step 2: Convert to fraction form
    78.85/108.94 = 72.77/x
  3. Step 3: Cross multiply
    78.85x = 108.94 × 72.77
  4. Step 4: Simplify right side
    78.85x = 7,927.56
  5. Step 5: Solve for x
    x = 7,927.56/78.85
  6. Step 6: Final answer
    x = 100.54

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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.