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Finding the Fourth Proportional to 86.85, 130.02 and 78.74

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Solution

The fourth proportional to 86.85, 130.02 and 78.74 is: 117.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.85 : 130.02 = 78.74 : x
  2. Step 2: Convert to fraction form
    86.85/130.02 = 78.74/x
  3. Step 3: Cross multiply
    86.85x = 130.02 × 78.74
  4. Step 4: Simplify right side
    86.85x = 10,236.73
  5. Step 5: Solve for x
    x = 10,236.73/86.85
  6. Step 6: Final answer
    x = 117.87

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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.