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Finding the Fourth Proportional to 85.94, 128.78 and 66.74

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Solution

The fourth proportional to 85.94, 128.78 and 66.74 is: 100.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.94 : 128.78 = 66.74 : x
  2. Step 2: Convert to fraction form
    85.94/128.78 = 66.74/x
  3. Step 3: Cross multiply
    85.94x = 128.78 × 66.74
  4. Step 4: Simplify right side
    85.94x = 8,594.78
  5. Step 5: Solve for x
    x = 8,594.78/85.94
  6. Step 6: Final answer
    x = 100.01

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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.