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Finding the Fourth Proportional to 85.75, 128.69 and 45.25

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Solution

The fourth proportional to 85.75, 128.69 and 45.25 is: 67.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.75 : 128.69 = 45.25 : x
  2. Step 2: Convert to fraction form
    85.75/128.69 = 45.25/x
  3. Step 3: Cross multiply
    85.75x = 128.69 × 45.25
  4. Step 4: Simplify right side
    85.75x = 5,823.22
  5. Step 5: Solve for x
    x = 5,823.22/85.75
  6. Step 6: Final answer
    x = 67.91

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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.