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Finding the Fourth Proportional to 79.28, 109.35 and 61.80

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Solution

The fourth proportional to 79.28, 109.35 and 61.80 is: 85.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.28 : 109.35 = 61.80 : x
  2. Step 2: Convert to fraction form
    79.28/109.35 = 61.80/x
  3. Step 3: Cross multiply
    79.28x = 109.35 × 61.80
  4. Step 4: Simplify right side
    79.28x = 6,757.83
  5. Step 5: Solve for x
    x = 6,757.83/79.28
  6. Step 6: Final answer
    x = 85.24

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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.