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Finding the Fourth Proportional to 1,420.80, 2,131.73 and 640.57

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Solution

The fourth proportional to 1,420.80, 2,131.73 and 640.57 is: 961.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.80 : 2,131.73 = 640.57 : x
  2. Step 2: Convert to fraction form
    1,420.80/2,131.73 = 640.57/x
  3. Step 3: Cross multiply
    1,420.80x = 2,131.73 × 640.57
  4. Step 4: Simplify right side
    1,420.80x = 1,365,518.56
  5. Step 5: Solve for x
    x = 1,365,518.56/1,420.80
  6. Step 6: Final answer
    x = 961.09

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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.