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Finding the Fourth Proportional to 811.89, 1,121.15 and 517.25

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Solution

The fourth proportional to 811.89, 1,121.15 and 517.25 is: 714.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.89 : 1,121.15 = 517.25 : x
  2. Step 2: Convert to fraction form
    811.89/1,121.15 = 517.25/x
  3. Step 3: Cross multiply
    811.89x = 1,121.15 × 517.25
  4. Step 4: Simplify right side
    811.89x = 579,914.84
  5. Step 5: Solve for x
    x = 579,914.84/811.89
  6. Step 6: Final answer
    x = 714.28

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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.