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Finding the Fourth Proportional to 86.32, 128.93 and 85.87

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Solution

The fourth proportional to 86.32, 128.93 and 85.87 is: 128.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.32 : 128.93 = 85.87 : x
  2. Step 2: Convert to fraction form
    86.32/128.93 = 85.87/x
  3. Step 3: Cross multiply
    86.32x = 128.93 × 85.87
  4. Step 4: Simplify right side
    86.32x = 11,071.22
  5. Step 5: Solve for x
    x = 11,071.22/86.32
  6. Step 6: Final answer
    x = 128.26

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Why These Related Problems?

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