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Finding the Fourth Proportional to 858.39, 1,287.31 and 281.13

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Solution

The fourth proportional to 858.39, 1,287.31 and 281.13 is: 421.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.39 : 1,287.31 = 281.13 : x
  2. Step 2: Convert to fraction form
    858.39/1,287.31 = 281.13/x
  3. Step 3: Cross multiply
    858.39x = 1,287.31 × 281.13
  4. Step 4: Simplify right side
    858.39x = 361,901.46
  5. Step 5: Solve for x
    x = 361,901.46/858.39
  6. Step 6: Final answer
    x = 421.60

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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.