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Finding the Fourth Proportional to 85.79, 128.01 and 76.71

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Solution

The fourth proportional to 85.79, 128.01 and 76.71 is: 114.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.79 : 128.01 = 76.71 : x
  2. Step 2: Convert to fraction form
    85.79/128.01 = 76.71/x
  3. Step 3: Cross multiply
    85.79x = 128.01 × 76.71
  4. Step 4: Simplify right side
    85.79x = 9,819.84
  5. Step 5: Solve for x
    x = 9,819.84/85.79
  6. Step 6: Final answer
    x = 114.46

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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.