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Finding the Fourth Proportional to 128.65, 178.31 and 116.50

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Solution

The fourth proportional to 128.65, 178.31 and 116.50 is: 161.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.65 : 178.31 = 116.50 : x
  2. Step 2: Convert to fraction form
    128.65/178.31 = 116.50/x
  3. Step 3: Cross multiply
    128.65x = 178.31 × 116.50
  4. Step 4: Simplify right side
    128.65x = 20,773.12
  5. Step 5: Solve for x
    x = 20,773.12/128.65
  6. Step 6: Final answer
    x = 161.47

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.