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Finding the Fourth Proportional to 640.40, 961.20 and 315.98

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Solution

The fourth proportional to 640.40, 961.20 and 315.98 is: 474.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    640.40 : 961.20 = 315.98 : x
  2. Step 2: Convert to fraction form
    640.40/961.20 = 315.98/x
  3. Step 3: Cross multiply
    640.40x = 961.20 × 315.98
  4. Step 4: Simplify right side
    640.40x = 303,719.98
  5. Step 5: Solve for x
    x = 303,719.98/640.40
  6. Step 6: Final answer
    x = 474.27

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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.