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Finding the Fourth Proportional to 1,211.18, 1,671.43 and 687.21

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Solution

The fourth proportional to 1,211.18, 1,671.43 and 687.21 is: 948.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.18 : 1,671.43 = 687.21 : x
  2. Step 2: Convert to fraction form
    1,211.18/1,671.43 = 687.21/x
  3. Step 3: Cross multiply
    1,211.18x = 1,671.43 × 687.21
  4. Step 4: Simplify right side
    1,211.18x = 1,148,611.62
  5. Step 5: Solve for x
    x = 1,148,611.62/1,211.18
  6. Step 6: Final answer
    x = 948.34

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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.