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Finding the Fourth Proportional to 85.69, 128.45 and 65.49

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Solution

The fourth proportional to 85.69, 128.45 and 65.49 is: 98.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.69 : 128.45 = 65.49 : x
  2. Step 2: Convert to fraction form
    85.69/128.45 = 65.49/x
  3. Step 3: Cross multiply
    85.69x = 128.45 × 65.49
  4. Step 4: Simplify right side
    85.69x = 8,411.87
  5. Step 5: Solve for x
    x = 8,411.87/85.69
  6. Step 6: Final answer
    x = 98.16

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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.