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Finding the Fourth Proportional to 939.58, 1,408 and 666.21

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Solution

The fourth proportional to 939.58, 1,408 and 666.21 is: 998.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.58 : 1,408 = 666.21 : x
  2. Step 2: Convert to fraction form
    939.58/1,408 = 666.21/x
  3. Step 3: Cross multiply
    939.58x = 1,408 × 666.21
  4. Step 4: Simplify right side
    939.58x = 938,023.68
  5. Step 5: Solve for x
    x = 938,023.68/939.58
  6. Step 6: Final answer
    x = 998.34

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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.