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Finding the Fourth Proportional to 939.86, 1,409.79 and 426.50

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Solution

The fourth proportional to 939.86, 1,409.79 and 426.50 is: 639.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.86 : 1,409.79 = 426.50 : x
  2. Step 2: Convert to fraction form
    939.86/1,409.79 = 426.50/x
  3. Step 3: Cross multiply
    939.86x = 1,409.79 × 426.50
  4. Step 4: Simplify right side
    939.86x = 601,275.44
  5. Step 5: Solve for x
    x = 601,275.44/939.86
  6. Step 6: Final answer
    x = 639.75

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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.