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Finding the Fourth Proportional to 86.04, 128.90 and 71.69

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Solution

The fourth proportional to 86.04, 128.90 and 71.69 is: 107.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.04 : 128.90 = 71.69 : x
  2. Step 2: Convert to fraction form
    86.04/128.90 = 71.69/x
  3. Step 3: Cross multiply
    86.04x = 128.90 × 71.69
  4. Step 4: Simplify right side
    86.04x = 9,240.48
  5. Step 5: Solve for x
    x = 9,240.48/86.04
  6. Step 6: Final answer
    x = 107.40

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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.