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Finding the Fourth Proportional to 86.59, 129.95 and 79.75

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Solution

The fourth proportional to 86.59, 129.95 and 79.75 is: 119.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.59 : 129.95 = 79.75 : x
  2. Step 2: Convert to fraction form
    86.59/129.95 = 79.75/x
  3. Step 3: Cross multiply
    86.59x = 129.95 × 79.75
  4. Step 4: Simplify right side
    86.59x = 10,364.02
  5. Step 5: Solve for x
    x = 10,364.02/86.59
  6. Step 6: Final answer
    x = 119.70

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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.