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Finding the Fourth Proportional to 891.21, 1,229.90 and 518.31

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Solution

The fourth proportional to 891.21, 1,229.90 and 518.31 is: 715.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    891.21 : 1,229.90 = 518.31 : x
  2. Step 2: Convert to fraction form
    891.21/1,229.90 = 518.31/x
  3. Step 3: Cross multiply
    891.21x = 1,229.90 × 518.31
  4. Step 4: Simplify right side
    891.21x = 637,466.88
  5. Step 5: Solve for x
    x = 637,466.88/891.21
  6. Step 6: Final answer
    x = 715.28

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.