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Finding the Fourth Proportional to 85.98, 128.91 and 45.42

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Solution

The fourth proportional to 85.98, 128.91 and 45.42 is: 68.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.98 : 128.91 = 45.42 : x
  2. Step 2: Convert to fraction form
    85.98/128.91 = 45.42/x
  3. Step 3: Cross multiply
    85.98x = 128.91 × 45.42
  4. Step 4: Simplify right side
    85.98x = 5,855.09
  5. Step 5: Solve for x
    x = 5,855.09/85.98
  6. Step 6: Final answer
    x = 68.10

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