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Finding the Fourth Proportional to 858.59, 1,287.86 and 209.31

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Solution

The fourth proportional to 858.59, 1,287.86 and 209.31 is: 313.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.59 : 1,287.86 = 209.31 : x
  2. Step 2: Convert to fraction form
    858.59/1,287.86 = 209.31/x
  3. Step 3: Cross multiply
    858.59x = 1,287.86 × 209.31
  4. Step 4: Simplify right side
    858.59x = 269,561.98
  5. Step 5: Solve for x
    x = 269,561.98/858.59
  6. Step 6: Final answer
    x = 313.96

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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.