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Finding the Fourth Proportional to 163.78, 245.35 and 86.65

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Solution

The fourth proportional to 163.78, 245.35 and 86.65 is: 129.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    163.78 : 245.35 = 86.65 : x
  2. Step 2: Convert to fraction form
    163.78/245.35 = 86.65/x
  3. Step 3: Cross multiply
    163.78x = 245.35 × 86.65
  4. Step 4: Simplify right side
    163.78x = 21,259.58
  5. Step 5: Solve for x
    x = 21,259.58/163.78
  6. Step 6: Final answer
    x = 129.81

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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.