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Finding the Fourth Proportional to 85.56, 128.43 and 45

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Solution

The fourth proportional to 85.56, 128.43 and 45 is: 67.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.56 : 128.43 = 45 : x
  2. Step 2: Convert to fraction form
    85.56/128.43 = 45/x
  3. Step 3: Cross multiply
    85.56x = 128.43 × 45
  4. Step 4: Simplify right side
    85.56x = 5,779.35
  5. Step 5: Solve for x
    x = 5,779.35/85.56
  6. Step 6: Final answer
    x = 67.55

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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.