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Finding the Fourth Proportional to 89.61, 133.70 and 78.18

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Solution

The fourth proportional to 89.61, 133.70 and 78.18 is: 116.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.61 : 133.70 = 78.18 : x
  2. Step 2: Convert to fraction form
    89.61/133.70 = 78.18/x
  3. Step 3: Cross multiply
    89.61x = 133.70 × 78.18
  4. Step 4: Simplify right side
    89.61x = 10,452.67
  5. Step 5: Solve for x
    x = 10,452.67/89.61
  6. Step 6: Final answer
    x = 116.65

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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.