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Finding the Fourth Proportional to 85, 127.49 and 78.57

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Solution

The fourth proportional to 85, 127.49 and 78.57 is: 117.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    85 : 127.49 = 78.57 : x
  2. Step 2: Convert to fraction form
    85/127.49 = 78.57/x
  3. Step 3: Cross multiply
    85x = 127.49 × 78.57
  4. Step 4: Simplify right side
    85x = 10,016.89
  5. Step 5: Solve for x
    x = 10,016.89/85
  6. Step 6: Final answer
    x = 117.85

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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.