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Finding the Fourth Proportional to 768.91, 1,155.34 and 639.31

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Solution

The fourth proportional to 768.91, 1,155.34 and 639.31 is: 960.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    768.91 : 1,155.34 = 639.31 : x
  2. Step 2: Convert to fraction form
    768.91/1,155.34 = 639.31/x
  3. Step 3: Cross multiply
    768.91x = 1,155.34 × 639.31
  4. Step 4: Simplify right side
    768.91x = 738,613.04
  5. Step 5: Solve for x
    x = 738,613.04/768.91
  6. Step 6: Final answer
    x = 960.60

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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.