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Finding the Fourth Proportional to 85.83, 128.99 and 79.75

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Solution

The fourth proportional to 85.83, 128.99 and 79.75 is: 119.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.83 : 128.99 = 79.75 : x
  2. Step 2: Convert to fraction form
    85.83/128.99 = 79.75/x
  3. Step 3: Cross multiply
    85.83x = 128.99 × 79.75
  4. Step 4: Simplify right side
    85.83x = 10,287.31
  5. Step 5: Solve for x
    x = 10,287.31/85.83
  6. Step 6: Final answer
    x = 119.86

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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.