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Finding the Fourth Proportional to 939.84, 1,297.14 and 645.78

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Solution

The fourth proportional to 939.84, 1,297.14 and 645.78 is: 891.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.84 : 1,297.14 = 645.78 : x
  2. Step 2: Convert to fraction form
    939.84/1,297.14 = 645.78/x
  3. Step 3: Cross multiply
    939.84x = 1,297.14 × 645.78
  4. Step 4: Simplify right side
    939.84x = 837,667.07
  5. Step 5: Solve for x
    x = 837,667.07/939.84
  6. Step 6: Final answer
    x = 891.29

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.