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Finding the Fourth Proportional to 826.80, 1,239.24 and 643.92

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Solution

The fourth proportional to 826.80, 1,239.24 and 643.92 is: 965.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    826.80 : 1,239.24 = 643.92 : x
  2. Step 2: Convert to fraction form
    826.80/1,239.24 = 643.92/x
  3. Step 3: Cross multiply
    826.80x = 1,239.24 × 643.92
  4. Step 4: Simplify right side
    826.80x = 797,971.42
  5. Step 5: Solve for x
    x = 797,971.42/826.80
  6. Step 6: Final answer
    x = 965.13

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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.