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Finding the Fourth Proportional to 216.80, 325.20 and 79.85

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Solution

The fourth proportional to 216.80, 325.20 and 79.85 is: 119.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    216.80 : 325.20 = 79.85 : x
  2. Step 2: Convert to fraction form
    216.80/325.20 = 79.85/x
  3. Step 3: Cross multiply
    216.80x = 325.20 × 79.85
  4. Step 4: Simplify right side
    216.80x = 25,967.22
  5. Step 5: Solve for x
    x = 25,967.22/216.80
  6. Step 6: Final answer
    x = 119.78

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.