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Finding the Fourth Proportional to 83.40, 115.22 and 78.68

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Solution

The fourth proportional to 83.40, 115.22 and 78.68 is: 108.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    83.40 : 115.22 = 78.68 : x
  2. Step 2: Convert to fraction form
    83.40/115.22 = 78.68/x
  3. Step 3: Cross multiply
    83.40x = 115.22 × 78.68
  4. Step 4: Simplify right side
    83.40x = 9,065.51
  5. Step 5: Solve for x
    x = 9,065.51/83.40
  6. Step 6: Final answer
    x = 108.70

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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.