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Finding the Fourth Proportional to 948.70, 1,422.37 and 639.78

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Solution

The fourth proportional to 948.70, 1,422.37 and 639.78 is: 959.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    948.70 : 1,422.37 = 639.78 : x
  2. Step 2: Convert to fraction form
    948.70/1,422.37 = 639.78/x
  3. Step 3: Cross multiply
    948.70x = 1,422.37 × 639.78
  4. Step 4: Simplify right side
    948.70x = 910,000.68
  5. Step 5: Solve for x
    x = 910,000.68/948.70
  6. Step 6: Final answer
    x = 959.21

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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.