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Finding the Fourth Proportional to 811.36, 1,217.22 and 421.24

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Solution

The fourth proportional to 811.36, 1,217.22 and 421.24 is: 631.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.36 : 1,217.22 = 421.24 : x
  2. Step 2: Convert to fraction form
    811.36/1,217.22 = 421.24/x
  3. Step 3: Cross multiply
    811.36x = 1,217.22 × 421.24
  4. Step 4: Simplify right side
    811.36x = 512,741.75
  5. Step 5: Solve for x
    x = 512,741.75/811.36
  6. Step 6: Final answer
    x = 631.95

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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.