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Finding the Fourth Proportional to 85.67, 128.50 and 68.76

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Solution

The fourth proportional to 85.67, 128.50 and 68.76 is: 103.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.67 : 128.50 = 68.76 : x
  2. Step 2: Convert to fraction form
    85.67/128.50 = 68.76/x
  3. Step 3: Cross multiply
    85.67x = 128.50 × 68.76
  4. Step 4: Simplify right side
    85.67x = 8,835.66
  5. Step 5: Solve for x
    x = 8,835.66/85.67
  6. Step 6: Final answer
    x = 103.14

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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.