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Finding the Fourth Proportional to 813.99, 1,220.40 and 380.91

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Solution

The fourth proportional to 813.99, 1,220.40 and 380.91 is: 571.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.99 : 1,220.40 = 380.91 : x
  2. Step 2: Convert to fraction form
    813.99/1,220.40 = 380.91/x
  3. Step 3: Cross multiply
    813.99x = 1,220.40 × 380.91
  4. Step 4: Simplify right side
    813.99x = 464,855.51
  5. Step 5: Solve for x
    x = 464,855.51/813.99
  6. Step 6: Final answer
    x = 571.09

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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.