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Finding the Fourth Proportional to 86.95, 129.66 and 86.18

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Solution

The fourth proportional to 86.95, 129.66 and 86.18 is: 128.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.95 : 129.66 = 86.18 : x
  2. Step 2: Convert to fraction form
    86.95/129.66 = 86.18/x
  3. Step 3: Cross multiply
    86.95x = 129.66 × 86.18
  4. Step 4: Simplify right side
    86.95x = 11,173.02
  5. Step 5: Solve for x
    x = 11,173.02/86.95
  6. Step 6: Final answer
    x = 128.50

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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.