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Finding the Fourth Proportional to 990.72, 1,367.12 and 571.20

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Solution

The fourth proportional to 990.72, 1,367.12 and 571.20 is: 788.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.72 : 1,367.12 = 571.20 : x
  2. Step 2: Convert to fraction form
    990.72/1,367.12 = 571.20/x
  3. Step 3: Cross multiply
    990.72x = 1,367.12 × 571.20
  4. Step 4: Simplify right side
    990.72x = 780,898.94
  5. Step 5: Solve for x
    x = 780,898.94/990.72
  6. Step 6: Final answer
    x = 788.21

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.