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Finding the Fourth Proportional to 85.86, 128.52 and 79.20

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Solution

The fourth proportional to 85.86, 128.52 and 79.20 is: 118.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.86 : 128.52 = 79.20 : x
  2. Step 2: Convert to fraction form
    85.86/128.52 = 79.20/x
  3. Step 3: Cross multiply
    85.86x = 128.52 × 79.20
  4. Step 4: Simplify right side
    85.86x = 10,178.78
  5. Step 5: Solve for x
    x = 10,178.78/85.86
  6. Step 6: Final answer
    x = 118.55

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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.