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Finding the Fourth Proportional to 939.32, 1,409.34 and 391.40

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Solution

The fourth proportional to 939.32, 1,409.34 and 391.40 is: 587.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.32 : 1,409.34 = 391.40 : x
  2. Step 2: Convert to fraction form
    939.32/1,409.34 = 391.40/x
  3. Step 3: Cross multiply
    939.32x = 1,409.34 × 391.40
  4. Step 4: Simplify right side
    939.32x = 551,615.68
  5. Step 5: Solve for x
    x = 551,615.68/939.32
  6. Step 6: Final answer
    x = 587.25

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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.