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Finding the Fourth Proportional to 871.28, 1,306.20 and 640.16

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Solution

The fourth proportional to 871.28, 1,306.20 and 640.16 is: 959.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    871.28 : 1,306.20 = 640.16 : x
  2. Step 2: Convert to fraction form
    871.28/1,306.20 = 640.16/x
  3. Step 3: Cross multiply
    871.28x = 1,306.20 × 640.16
  4. Step 4: Simplify right side
    871.28x = 836,176.99
  5. Step 5: Solve for x
    x = 836,176.99/871.28
  6. Step 6: Final answer
    x = 959.71

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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.