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Finding the Fourth Proportional to 939.70, 1,409.58 and 391.51

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Solution

The fourth proportional to 939.70, 1,409.58 and 391.51 is: 587.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.70 : 1,409.58 = 391.51 : x
  2. Step 2: Convert to fraction form
    939.70/1,409.58 = 391.51/x
  3. Step 3: Cross multiply
    939.70x = 1,409.58 × 391.51
  4. Step 4: Simplify right side
    939.70x = 551,864.67
  5. Step 5: Solve for x
    x = 551,864.67/939.70
  6. Step 6: Final answer
    x = 587.28

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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.