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Finding the Fourth Proportional to 858.90, 1,287.63 and 338.61

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Solution

The fourth proportional to 858.90, 1,287.63 and 338.61 is: 507.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.90 : 1,287.63 = 338.61 : x
  2. Step 2: Convert to fraction form
    858.90/1,287.63 = 338.61/x
  3. Step 3: Cross multiply
    858.90x = 1,287.63 × 338.61
  4. Step 4: Simplify right side
    858.90x = 436,004.39
  5. Step 5: Solve for x
    x = 436,004.39/858.90
  6. Step 6: Final answer
    x = 507.63

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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.