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Finding the Fourth Proportional to 85.84, 128.72 and 55.36

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Solution

The fourth proportional to 85.84, 128.72 and 55.36 is: 83.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.84 : 128.72 = 55.36 : x
  2. Step 2: Convert to fraction form
    85.84/128.72 = 55.36/x
  3. Step 3: Cross multiply
    85.84x = 128.72 × 55.36
  4. Step 4: Simplify right side
    85.84x = 7,125.94
  5. Step 5: Solve for x
    x = 7,125.94/85.84
  6. Step 6: Final answer
    x = 83.01

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.