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Finding the Fourth Proportional to 858.21, 1,287.74 and 425.13

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Solution

The fourth proportional to 858.21, 1,287.74 and 425.13 is: 637.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.21 : 1,287.74 = 425.13 : x
  2. Step 2: Convert to fraction form
    858.21/1,287.74 = 425.13/x
  3. Step 3: Cross multiply
    858.21x = 1,287.74 × 425.13
  4. Step 4: Simplify right side
    858.21x = 547,454.78
  5. Step 5: Solve for x
    x = 547,454.78/858.21
  6. Step 6: Final answer
    x = 637.90

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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.