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Finding the Fourth Proportional to 286.79, 430.21 and 78.56

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Solution

The fourth proportional to 286.79, 430.21 and 78.56 is: 117.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    286.79 : 430.21 = 78.56 : x
  2. Step 2: Convert to fraction form
    286.79/430.21 = 78.56/x
  3. Step 3: Cross multiply
    286.79x = 430.21 × 78.56
  4. Step 4: Simplify right side
    286.79x = 33,797.59
  5. Step 5: Solve for x
    x = 33,797.59/286.79
  6. Step 6: Final answer
    x = 117.85

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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.