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Finding the Fourth Proportional to 85.95, 128.09 and 76.32

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Solution

The fourth proportional to 85.95, 128.09 and 76.32 is: 113.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.95 : 128.09 = 76.32 : x
  2. Step 2: Convert to fraction form
    85.95/128.09 = 76.32/x
  3. Step 3: Cross multiply
    85.95x = 128.09 × 76.32
  4. Step 4: Simplify right side
    85.95x = 9,776.02
  5. Step 5: Solve for x
    x = 9,776.02/85.95
  6. Step 6: Final answer
    x = 113.74

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.