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Finding the Fourth Proportional to 79.65, 109.78 and 66.49

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Solution

The fourth proportional to 79.65, 109.78 and 66.49 is: 91.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.65 : 109.78 = 66.49 : x
  2. Step 2: Convert to fraction form
    79.65/109.78 = 66.49/x
  3. Step 3: Cross multiply
    79.65x = 109.78 × 66.49
  4. Step 4: Simplify right side
    79.65x = 7,299.08
  5. Step 5: Solve for x
    x = 7,299.08/79.65
  6. Step 6: Final answer
    x = 91.64

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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.