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Finding the Fourth Proportional to 855.90, 1,282.59 and 639.36

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Solution

The fourth proportional to 855.90, 1,282.59 and 639.36 is: 958.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    855.90 : 1,282.59 = 639.36 : x
  2. Step 2: Convert to fraction form
    855.90/1,282.59 = 639.36/x
  3. Step 3: Cross multiply
    855.90x = 1,282.59 × 639.36
  4. Step 4: Simplify right side
    855.90x = 820,036.74
  5. Step 5: Solve for x
    x = 820,036.74/855.90
  6. Step 6: Final answer
    x = 958.10

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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.