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Finding the Fourth Proportional to 857.86, 1,286.80 and 208.60

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Solution

The fourth proportional to 857.86, 1,286.80 and 208.60 is: 312.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.86 : 1,286.80 = 208.60 : x
  2. Step 2: Convert to fraction form
    857.86/1,286.80 = 208.60/x
  3. Step 3: Cross multiply
    857.86x = 1,286.80 × 208.60
  4. Step 4: Simplify right side
    857.86x = 268,420.05
  5. Step 5: Solve for x
    x = 268,420.05/857.86
  6. Step 6: Final answer
    x = 312.89

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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.