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Finding the Fourth Proportional to 85.96, 128.96 and 45.43

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Solution

The fourth proportional to 85.96, 128.96 and 45.43 is: 68.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.96 : 128.96 = 45.43 : x
  2. Step 2: Convert to fraction form
    85.96/128.96 = 45.43/x
  3. Step 3: Cross multiply
    85.96x = 128.96 × 45.43
  4. Step 4: Simplify right side
    85.96x = 5,858.77
  5. Step 5: Solve for x
    x = 5,858.77/85.96
  6. Step 6: Final answer
    x = 68.16

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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.