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Finding the Fourth Proportional to 931.21, 1,396.81 and 442.78

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Solution

The fourth proportional to 931.21, 1,396.81 and 442.78 is: 664.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    931.21 : 1,396.81 = 442.78 : x
  2. Step 2: Convert to fraction form
    931.21/1,396.81 = 442.78/x
  3. Step 3: Cross multiply
    931.21x = 1,396.81 × 442.78
  4. Step 4: Simplify right side
    931.21x = 618,476.59
  5. Step 5: Solve for x
    x = 618,476.59/931.21
  6. Step 6: Final answer
    x = 664.17

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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.