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Finding the Fourth Proportional to 939.78, 1,409.94 and 290.70

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Solution

The fourth proportional to 939.78, 1,409.94 and 290.70 is: 436.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.78 : 1,409.94 = 290.70 : x
  2. Step 2: Convert to fraction form
    939.78/1,409.94 = 290.70/x
  3. Step 3: Cross multiply
    939.78x = 1,409.94 × 290.70
  4. Step 4: Simplify right side
    939.78x = 409,869.56
  5. Step 5: Solve for x
    x = 409,869.56/939.78
  6. Step 6: Final answer
    x = 436.13

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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.