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Finding the Fourth Proportional to 85.53, 128.14 and 69.20

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Solution

The fourth proportional to 85.53, 128.14 and 69.20 is: 103.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.53 : 128.14 = 69.20 : x
  2. Step 2: Convert to fraction form
    85.53/128.14 = 69.20/x
  3. Step 3: Cross multiply
    85.53x = 128.14 × 69.20
  4. Step 4: Simplify right side
    85.53x = 8,867.29
  5. Step 5: Solve for x
    x = 8,867.29/85.53
  6. Step 6: Final answer
    x = 103.67

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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.