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Finding the Fourth Proportional to 86.24, 128.74 and 71.05

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Solution

The fourth proportional to 86.24, 128.74 and 71.05 is: 106.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.24 : 128.74 = 71.05 : x
  2. Step 2: Convert to fraction form
    86.24/128.74 = 71.05/x
  3. Step 3: Cross multiply
    86.24x = 128.74 × 71.05
  4. Step 4: Simplify right side
    86.24x = 9,146.33
  5. Step 5: Solve for x
    x = 9,146.33/86.24
  6. Step 6: Final answer
    x = 106.06

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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.