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Finding the Fourth Proportional to 85.68, 127.92 and 71.28

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Solution

The fourth proportional to 85.68, 127.92 and 71.28 is: 106.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.68 : 127.92 = 71.28 : x
  2. Step 2: Convert to fraction form
    85.68/127.92 = 71.28/x
  3. Step 3: Cross multiply
    85.68x = 127.92 × 71.28
  4. Step 4: Simplify right side
    85.68x = 9,118.14
  5. Step 5: Solve for x
    x = 9,118.14/85.68
  6. Step 6: Final answer
    x = 106.42

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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.