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Finding the Fourth Proportional to 1,390.91, 2,086.43 and 813.38

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Solution

The fourth proportional to 1,390.91, 2,086.43 and 813.38 is: 1,220.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.91 : 2,086.43 = 813.38 : x
  2. Step 2: Convert to fraction form
    1,390.91/2,086.43 = 813.38/x
  3. Step 3: Cross multiply
    1,390.91x = 2,086.43 × 813.38
  4. Step 4: Simplify right side
    1,390.91x = 1,697,045.93
  5. Step 5: Solve for x
    x = 1,697,045.93/1,390.91
  6. Step 6: Final answer
    x = 1,220.10

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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.