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Finding the Fourth Proportional to 76.79, 105.71 and 66.57

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Solution

The fourth proportional to 76.79, 105.71 and 66.57 is: 91.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.79 : 105.71 = 66.57 : x
  2. Step 2: Convert to fraction form
    76.79/105.71 = 66.57/x
  3. Step 3: Cross multiply
    76.79x = 105.71 × 66.57
  4. Step 4: Simplify right side
    76.79x = 7,036.78
  5. Step 5: Solve for x
    x = 7,036.78/76.79
  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.