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Finding the Fourth Proportional to 858.15, 1,287.21 and 208.88

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Solution

The fourth proportional to 858.15, 1,287.21 and 208.88 is: 313.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.15 : 1,287.21 = 208.88 : x
  2. Step 2: Convert to fraction form
    858.15/1,287.21 = 208.88/x
  3. Step 3: Cross multiply
    858.15x = 1,287.21 × 208.88
  4. Step 4: Simplify right side
    858.15x = 268,872.42
  5. Step 5: Solve for x
    x = 268,872.42/858.15
  6. Step 6: Final answer
    x = 313.32

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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.