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Finding the Fourth Proportional to 79.40, 109.68 and 77.42

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Solution

The fourth proportional to 79.40, 109.68 and 77.42 is: 106.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.40 : 109.68 = 77.42 : x
  2. Step 2: Convert to fraction form
    79.40/109.68 = 77.42/x
  3. Step 3: Cross multiply
    79.40x = 109.68 × 77.42
  4. Step 4: Simplify right side
    79.40x = 8,491.43
  5. Step 5: Solve for x
    x = 8,491.43/79.40
  6. Step 6: Final answer
    x = 106.94

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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.