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Finding the Fourth Proportional to 808.90, 1,213.47 and 315.21

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Solution

The fourth proportional to 808.90, 1,213.47 and 315.21 is: 472.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    808.90 : 1,213.47 = 315.21 : x
  2. Step 2: Convert to fraction form
    808.90/1,213.47 = 315.21/x
  3. Step 3: Cross multiply
    808.90x = 1,213.47 × 315.21
  4. Step 4: Simplify right side
    808.90x = 382,496.30
  5. Step 5: Solve for x
    x = 382,496.30/808.90
  6. Step 6: Final answer
    x = 472.86

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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.