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Finding the Fourth Proportional to 86.12, 128.55 and 79.77

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Solution

The fourth proportional to 86.12, 128.55 and 79.77 is: 119.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.12 : 128.55 = 79.77 : x
  2. Step 2: Convert to fraction form
    86.12/128.55 = 79.77/x
  3. Step 3: Cross multiply
    86.12x = 128.55 × 79.77
  4. Step 4: Simplify right side
    86.12x = 10,255.21
  5. Step 5: Solve for x
    x = 10,255.21/86.12
  6. Step 6: Final answer
    x = 119.08

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.