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Finding the Fourth Proportional to 100.78, 150.86 and 85.59

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Solution

The fourth proportional to 100.78, 150.86 and 85.59 is: 128.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.78 : 150.86 = 85.59 : x
  2. Step 2: Convert to fraction form
    100.78/150.86 = 85.59/x
  3. Step 3: Cross multiply
    100.78x = 150.86 × 85.59
  4. Step 4: Simplify right side
    100.78x = 12,912.32
  5. Step 5: Solve for x
    x = 12,912.32/100.78
  6. Step 6: Final answer
    x = 128.13

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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.