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Finding the Fourth Proportional to 820.78, 1,229.09 and 491.51

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Solution

The fourth proportional to 820.78, 1,229.09 and 491.51 is: 736.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.78 : 1,229.09 = 491.51 : x
  2. Step 2: Convert to fraction form
    820.78/1,229.09 = 491.51/x
  3. Step 3: Cross multiply
    820.78x = 1,229.09 × 491.51
  4. Step 4: Simplify right side
    820.78x = 604,111.25
  5. Step 5: Solve for x
    x = 604,111.25/820.78
  6. Step 6: Final answer
    x = 736.03

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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.