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Finding the Fourth Proportional to 1,290.80, 1,936.20 and 521.12

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Solution

The fourth proportional to 1,290.80, 1,936.20 and 521.12 is: 781.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.80 : 1,936.20 = 521.12 : x
  2. Step 2: Convert to fraction form
    1,290.80/1,936.20 = 521.12/x
  3. Step 3: Cross multiply
    1,290.80x = 1,936.20 × 521.12
  4. Step 4: Simplify right side
    1,290.80x = 1,008,992.54
  5. Step 5: Solve for x
    x = 1,008,992.54/1,290.80
  6. Step 6: Final answer
    x = 781.68

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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.