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Finding the Fourth Proportional to 86.75, 129.40 and 79.05

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Solution

The fourth proportional to 86.75, 129.40 and 79.05 is: 117.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.75 : 129.40 = 79.05 : x
  2. Step 2: Convert to fraction form
    86.75/129.40 = 79.05/x
  3. Step 3: Cross multiply
    86.75x = 129.40 × 79.05
  4. Step 4: Simplify right side
    86.75x = 10,229.07
  5. Step 5: Solve for x
    x = 10,229.07/86.75
  6. Step 6: Final answer
    x = 117.91

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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.