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Finding the Fourth Proportional to 86.91, 129.63 and 74.15

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Solution

The fourth proportional to 86.91, 129.63 and 74.15 is: 110.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.91 : 129.63 = 74.15 : x
  2. Step 2: Convert to fraction form
    86.91/129.63 = 74.15/x
  3. Step 3: Cross multiply
    86.91x = 129.63 × 74.15
  4. Step 4: Simplify right side
    86.91x = 9,611.42
  5. Step 5: Solve for x
    x = 9,611.42/86.91
  6. Step 6: Final answer
    x = 110.59

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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.