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Finding the Fourth Proportional to 86.13, 128.57 and 71.55

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Solution

The fourth proportional to 86.13, 128.57 and 71.55 is: 106.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.13 : 128.57 = 71.55 : x
  2. Step 2: Convert to fraction form
    86.13/128.57 = 71.55/x
  3. Step 3: Cross multiply
    86.13x = 128.57 × 71.55
  4. Step 4: Simplify right side
    86.13x = 9,199.23
  5. Step 5: Solve for x
    x = 9,199.23/86.13
  6. Step 6: Final answer
    x = 106.81

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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.