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Finding the Fourth Proportional to 639.98, 956.42 and 515.21

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Solution

The fourth proportional to 639.98, 956.42 and 515.21 is: 769.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.98 : 956.42 = 515.21 : x
  2. Step 2: Convert to fraction form
    639.98/956.42 = 515.21/x
  3. Step 3: Cross multiply
    639.98x = 956.42 × 515.21
  4. Step 4: Simplify right side
    639.98x = 492,749.79
  5. Step 5: Solve for x
    x = 492,749.79/639.98
  6. Step 6: Final answer
    x = 769.95

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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.