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Finding the Fourth Proportional to 85.48, 128.19 and 51.25

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Solution

The fourth proportional to 85.48, 128.19 and 51.25 is: 76.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.48 : 128.19 = 51.25 : x
  2. Step 2: Convert to fraction form
    85.48/128.19 = 51.25/x
  3. Step 3: Cross multiply
    85.48x = 128.19 × 51.25
  4. Step 4: Simplify right side
    85.48x = 6,569.74
  5. Step 5: Solve for x
    x = 6,569.74/85.48
  6. Step 6: Final answer
    x = 76.86

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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.