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Finding the Fourth Proportional to 85.16, 128.25 and 77.13

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Solution

The fourth proportional to 85.16, 128.25 and 77.13 is: 116.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.16 : 128.25 = 77.13 : x
  2. Step 2: Convert to fraction form
    85.16/128.25 = 77.13/x
  3. Step 3: Cross multiply
    85.16x = 128.25 × 77.13
  4. Step 4: Simplify right side
    85.16x = 9,891.92
  5. Step 5: Solve for x
    x = 9,891.92/85.16
  6. Step 6: Final answer
    x = 116.15

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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.