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Finding the Fourth Proportional to 86.43, 129.78 and 70.50

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Solution

The fourth proportional to 86.43, 129.78 and 70.50 is: 105.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.43 : 129.78 = 70.50 : x
  2. Step 2: Convert to fraction form
    86.43/129.78 = 70.50/x
  3. Step 3: Cross multiply
    86.43x = 129.78 × 70.50
  4. Step 4: Simplify right side
    86.43x = 9,149.49
  5. Step 5: Solve for x
    x = 9,149.49/86.43
  6. Step 6: Final answer
    x = 105.86

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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.