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Finding the Fourth Proportional to 89.67, 123.78 and 66.40

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Solution

The fourth proportional to 89.67, 123.78 and 66.40 is: 91.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.67 : 123.78 = 66.40 : x
  2. Step 2: Convert to fraction form
    89.67/123.78 = 66.40/x
  3. Step 3: Cross multiply
    89.67x = 123.78 × 66.40
  4. Step 4: Simplify right side
    89.67x = 8,218.99
  5. Step 5: Solve for x
    x = 8,218.99/89.67
  6. Step 6: Final answer
    x = 91.66

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.