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Finding the Fourth Proportional to 85.10, 128.57 and 84.38

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Solution

The fourth proportional to 85.10, 128.57 and 84.38 is: 127.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.10 : 128.57 = 84.38 : x
  2. Step 2: Convert to fraction form
    85.10/128.57 = 84.38/x
  3. Step 3: Cross multiply
    85.10x = 128.57 × 84.38
  4. Step 4: Simplify right side
    85.10x = 10,847.67
  5. Step 5: Solve for x
    x = 10,847.67/85.10
  6. Step 6: Final answer
    x = 127.48

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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.