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Finding the Fourth Proportional to 191.40, 287.21 and 81.71

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Solution

The fourth proportional to 191.40, 287.21 and 81.71 is: 122.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    191.40 : 287.21 = 81.71 : x
  2. Step 2: Convert to fraction form
    191.40/287.21 = 81.71/x
  3. Step 3: Cross multiply
    191.40x = 287.21 × 81.71
  4. Step 4: Simplify right side
    191.40x = 23,467.36
  5. Step 5: Solve for x
    x = 23,467.36/191.40
  6. Step 6: Final answer
    x = 122.61

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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.