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Finding the Fourth Proportional to 859.90, 1,187.38 and 639.83

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Solution

The fourth proportional to 859.90, 1,187.38 and 639.83 is: 883.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.90 : 1,187.38 = 639.83 : x
  2. Step 2: Convert to fraction form
    859.90/1,187.38 = 639.83/x
  3. Step 3: Cross multiply
    859.90x = 1,187.38 × 639.83
  4. Step 4: Simplify right side
    859.90x = 759,721.35
  5. Step 5: Solve for x
    x = 759,721.35/859.90
  6. Step 6: Final answer
    x = 883.50

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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.