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Finding the Fourth Proportional to 85.50, 128.49 and 63.90

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Solution

The fourth proportional to 85.50, 128.49 and 63.90 is: 96.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.50 : 128.49 = 63.90 : x
  2. Step 2: Convert to fraction form
    85.50/128.49 = 63.90/x
  3. Step 3: Cross multiply
    85.50x = 128.49 × 63.90
  4. Step 4: Simplify right side
    85.50x = 8,210.51
  5. Step 5: Solve for x
    x = 8,210.51/85.50
  6. Step 6: Final answer
    x = 96.03

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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.