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Finding the Fourth Proportional to 79.11, 109.28 and 61.70

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Solution

The fourth proportional to 79.11, 109.28 and 61.70 is: 85.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.11 : 109.28 = 61.70 : x
  2. Step 2: Convert to fraction form
    79.11/109.28 = 61.70/x
  3. Step 3: Cross multiply
    79.11x = 109.28 × 61.70
  4. Step 4: Simplify right side
    79.11x = 6,742.18
  5. Step 5: Solve for x
    x = 6,742.18/79.11
  6. Step 6: Final answer
    x = 85.23

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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.