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Finding the Fourth Proportional to 85.35, 128.02 and 71.80

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Solution

The fourth proportional to 85.35, 128.02 and 71.80 is: 107.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.35 : 128.02 = 71.80 : x
  2. Step 2: Convert to fraction form
    85.35/128.02 = 71.80/x
  3. Step 3: Cross multiply
    85.35x = 128.02 × 71.80
  4. Step 4: Simplify right side
    85.35x = 9,191.84
  5. Step 5: Solve for x
    x = 9,191.84/85.35
  6. Step 6: Final answer
    x = 107.70

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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.