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Finding the Fourth Proportional to 1,420.83, 2,131.99 and 640.69

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Solution

The fourth proportional to 1,420.83, 2,131.99 and 640.69 is: 961.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.83 : 2,131.99 = 640.69 : x
  2. Step 2: Convert to fraction form
    1,420.83/2,131.99 = 640.69/x
  3. Step 3: Cross multiply
    1,420.83x = 2,131.99 × 640.69
  4. Step 4: Simplify right side
    1,420.83x = 1,365,937.74
  5. Step 5: Solve for x
    x = 1,365,937.74/1,420.83
  6. Step 6: Final answer
    x = 961.37

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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.