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Finding the Fourth Proportional to 1,419.40, 2,129.01 and 639.46

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Solution

The fourth proportional to 1,419.40, 2,129.01 and 639.46 is: 959.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,419.40 : 2,129.01 = 639.46 : x
  2. Step 2: Convert to fraction form
    1,419.40/2,129.01 = 639.46/x
  3. Step 3: Cross multiply
    1,419.40x = 2,129.01 × 639.46
  4. Step 4: Simplify right side
    1,419.40x = 1,361,416.73
  5. Step 5: Solve for x
    x = 1,361,416.73/1,419.40
  6. Step 6: Final answer
    x = 959.15

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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.