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Finding the Fourth Proportional to 86.16, 128.31 and 85.80

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Solution

The fourth proportional to 86.16, 128.31 and 85.80 is: 127.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.16 : 128.31 = 85.80 : x
  2. Step 2: Convert to fraction form
    86.16/128.31 = 85.80/x
  3. Step 3: Cross multiply
    86.16x = 128.31 × 85.80
  4. Step 4: Simplify right side
    86.16x = 11,009.00
  5. Step 5: Solve for x
    x = 11,009.00/86.16
  6. Step 6: Final answer
    x = 127.77

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These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.