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Finding the Fourth Proportional to 811.44, 1,218.24 and 421.74

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Solution

The fourth proportional to 811.44, 1,218.24 and 421.74 is: 633.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.44 : 1,218.24 = 421.74 : x
  2. Step 2: Convert to fraction form
    811.44/1,218.24 = 421.74/x
  3. Step 3: Cross multiply
    811.44x = 1,218.24 × 421.74
  4. Step 4: Simplify right side
    811.44x = 513,780.54
  5. Step 5: Solve for x
    x = 513,780.54/811.44
  6. Step 6: Final answer
    x = 633.17

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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.