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Finding the Fourth Proportional to 811.21, 1,217.15 and 378.10

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Solution

The fourth proportional to 811.21, 1,217.15 and 378.10 is: 567.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.21 : 1,217.15 = 378.10 : x
  2. Step 2: Convert to fraction form
    811.21/1,217.15 = 378.10/x
  3. Step 3: Cross multiply
    811.21x = 1,217.15 × 378.10
  4. Step 4: Simplify right side
    811.21x = 460,202.52
  5. Step 5: Solve for x
    x = 460,202.52/811.21
  6. Step 6: Final answer
    x = 567.30

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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.