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Finding the Fourth Proportional to 85.68, 128.43 and 40.05

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Solution

The fourth proportional to 85.68, 128.43 and 40.05 is: 60.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.68 : 128.43 = 40.05 : x
  2. Step 2: Convert to fraction form
    85.68/128.43 = 40.05/x
  3. Step 3: Cross multiply
    85.68x = 128.43 × 40.05
  4. Step 4: Simplify right side
    85.68x = 5,143.62
  5. Step 5: Solve for x
    x = 5,143.62/85.68
  6. Step 6: Final answer
    x = 60.03

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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.