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Finding the Fourth Proportional to 85.80, 129.06 and 79.20

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Solution

The fourth proportional to 85.80, 129.06 and 79.20 is: 119.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.80 : 129.06 = 79.20 : x
  2. Step 2: Convert to fraction form
    85.80/129.06 = 79.20/x
  3. Step 3: Cross multiply
    85.80x = 129.06 × 79.20
  4. Step 4: Simplify right side
    85.80x = 10,221.55
  5. Step 5: Solve for x
    x = 10,221.55/85.80
  6. Step 6: Final answer
    x = 119.13

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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.