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Finding the Fourth Proportional to 807.79, 1,113.90 and 639.47

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Solution

The fourth proportional to 807.79, 1,113.90 and 639.47 is: 881.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    807.79 : 1,113.90 = 639.47 : x
  2. Step 2: Convert to fraction form
    807.79/1,113.90 = 639.47/x
  3. Step 3: Cross multiply
    807.79x = 1,113.90 × 639.47
  4. Step 4: Simplify right side
    807.79x = 712,305.63
  5. Step 5: Solve for x
    x = 712,305.63/807.79
  6. Step 6: Final answer
    x = 881.80

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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.