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Finding the Fourth Proportional to 919.23, 1,267.05 and 639.78

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Solution

The fourth proportional to 919.23, 1,267.05 and 639.78 is: 881.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.23 : 1,267.05 = 639.78 : x
  2. Step 2: Convert to fraction form
    919.23/1,267.05 = 639.78/x
  3. Step 3: Cross multiply
    919.23x = 1,267.05 × 639.78
  4. Step 4: Simplify right side
    919.23x = 810,633.25
  5. Step 5: Solve for x
    x = 810,633.25/919.23
  6. Step 6: Final answer
    x = 881.86

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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.