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Finding the Fourth Proportional to 85.08, 128.40 and 82.20

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Solution

The fourth proportional to 85.08, 128.40 and 82.20 is: 124.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.08 : 128.40 = 82.20 : x
  2. Step 2: Convert to fraction form
    85.08/128.40 = 82.20/x
  3. Step 3: Cross multiply
    85.08x = 128.40 × 82.20
  4. Step 4: Simplify right side
    85.08x = 10,554.48
  5. Step 5: Solve for x
    x = 10,554.48/85.08
  6. Step 6: Final answer
    x = 124.05

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.