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Finding the Fourth Proportional to 858.32, 1,287.48 and 425.78

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Solution

The fourth proportional to 858.32, 1,287.48 and 425.78 is: 638.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.32 : 1,287.48 = 425.78 : x
  2. Step 2: Convert to fraction form
    858.32/1,287.48 = 425.78/x
  3. Step 3: Cross multiply
    858.32x = 1,287.48 × 425.78
  4. Step 4: Simplify right side
    858.32x = 548,183.23
  5. Step 5: Solve for x
    x = 548,183.23/858.32
  6. Step 6: Final answer
    x = 638.67

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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.