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Finding the Fourth Proportional to 858.45, 1,287.67 and 209.19

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Solution

The fourth proportional to 858.45, 1,287.67 and 209.19 is: 313.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.45 : 1,287.67 = 209.19 : x
  2. Step 2: Convert to fraction form
    858.45/1,287.67 = 209.19/x
  3. Step 3: Cross multiply
    858.45x = 1,287.67 × 209.19
  4. Step 4: Simplify right side
    858.45x = 269,366.64
  5. Step 5: Solve for x
    x = 269,366.64/858.45
  6. Step 6: Final answer
    x = 313.78

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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.