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Finding the Fourth Proportional to 78.84, 108.94 and 72.78

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Solution

The fourth proportional to 78.84, 108.94 and 72.78 is: 100.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.84 : 108.94 = 72.78 : x
  2. Step 2: Convert to fraction form
    78.84/108.94 = 72.78/x
  3. Step 3: Cross multiply
    78.84x = 108.94 × 72.78
  4. Step 4: Simplify right side
    78.84x = 7,928.65
  5. Step 5: Solve for x
    x = 7,928.65/78.84
  6. Step 6: Final answer
    x = 100.57

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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.