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Finding the Fourth Proportional to 86.10, 128.94 and 70.92

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Solution

The fourth proportional to 86.10, 128.94 and 70.92 is: 106.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.10 : 128.94 = 70.92 : x
  2. Step 2: Convert to fraction form
    86.10/128.94 = 70.92/x
  3. Step 3: Cross multiply
    86.10x = 128.94 × 70.92
  4. Step 4: Simplify right side
    86.10x = 9,144.42
  5. Step 5: Solve for x
    x = 9,144.42/86.10
  6. Step 6: Final answer
    x = 106.21

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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.