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Finding the Fourth Proportional to 79.40, 118.16 and 77.80

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Solution

The fourth proportional to 79.40, 118.16 and 77.80 is: 115.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.40 : 118.16 = 77.80 : x
  2. Step 2: Convert to fraction form
    79.40/118.16 = 77.80/x
  3. Step 3: Cross multiply
    79.40x = 118.16 × 77.80
  4. Step 4: Simplify right side
    79.40x = 9,192.85
  5. Step 5: Solve for x
    x = 9,192.85/79.40
  6. Step 6: Final answer
    x = 115.78

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.