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Finding the Fourth Proportional to 85.53, 128.34 and 45

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Solution

The fourth proportional to 85.53, 128.34 and 45 is: 67.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.53 : 128.34 = 45 : x
  2. Step 2: Convert to fraction form
    85.53/128.34 = 45/x
  3. Step 3: Cross multiply
    85.53x = 128.34 × 45
  4. Step 4: Simplify right side
    85.53x = 5,775.30
  5. Step 5: Solve for x
    x = 5,775.30/85.53
  6. Step 6: Final answer
    x = 67.52

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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.