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Finding the Fourth Proportional to 100.31, 149.66 and 85.70

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Solution

The fourth proportional to 100.31, 149.66 and 85.70 is: 127.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.31 : 149.66 = 85.70 : x
  2. Step 2: Convert to fraction form
    100.31/149.66 = 85.70/x
  3. Step 3: Cross multiply
    100.31x = 149.66 × 85.70
  4. Step 4: Simplify right side
    100.31x = 12,824.69
  5. Step 5: Solve for x
    x = 12,824.69/100.31
  6. Step 6: Final answer
    x = 127.86

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.