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Finding the Fourth Proportional to 857.81, 1,286.72 and 208.55

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Solution

The fourth proportional to 857.81, 1,286.72 and 208.55 is: 312.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.81 : 1,286.72 = 208.55 : x
  2. Step 2: Convert to fraction form
    857.81/1,286.72 = 208.55/x
  3. Step 3: Cross multiply
    857.81x = 1,286.72 × 208.55
  4. Step 4: Simplify right side
    857.81x = 268,341.17
  5. Step 5: Solve for x
    x = 268,341.17/857.81
  6. Step 6: Final answer
    x = 312.82

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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.