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Finding the Fourth Proportional to 640.95, 961.21 and 208

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Solution

The fourth proportional to 640.95, 961.21 and 208 is: 311.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    640.95 : 961.21 = 208 : x
  2. Step 2: Convert to fraction form
    640.95/961.21 = 208/x
  3. Step 3: Cross multiply
    640.95x = 961.21 × 208
  4. Step 4: Simplify right side
    640.95x = 199,931.68
  5. Step 5: Solve for x
    x = 199,931.68/640.95
  6. Step 6: Final answer
    x = 311.93

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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.