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Finding the Fourth Proportional to 85.68, 128.54 and 67.40

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Solution

The fourth proportional to 85.68, 128.54 and 67.40 is: 101.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.68 : 128.54 = 67.40 : x
  2. Step 2: Convert to fraction form
    85.68/128.54 = 67.40/x
  3. Step 3: Cross multiply
    85.68x = 128.54 × 67.40
  4. Step 4: Simplify right side
    85.68x = 8,663.26
  5. Step 5: Solve for x
    x = 8,663.26/85.68
  6. Step 6: Final answer
    x = 101.11

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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.