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Finding the Fourth Proportional to 86.76, 130.20 and 78.84

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Solution

The fourth proportional to 86.76, 130.20 and 78.84 is: 118.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.76 : 130.20 = 78.84 : x
  2. Step 2: Convert to fraction form
    86.76/130.20 = 78.84/x
  3. Step 3: Cross multiply
    86.76x = 130.20 × 78.84
  4. Step 4: Simplify right side
    86.76x = 10,264.97
  5. Step 5: Solve for x
    x = 10,264.97/86.76
  6. Step 6: Final answer
    x = 118.31

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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.