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Finding the Fourth Proportional to 1,381.70, 2,072.78 and 642.05

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Solution

The fourth proportional to 1,381.70, 2,072.78 and 642.05 is: 963.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,381.70 : 2,072.78 = 642.05 : x
  2. Step 2: Convert to fraction form
    1,381.70/2,072.78 = 642.05/x
  3. Step 3: Cross multiply
    1,381.70x = 2,072.78 × 642.05
  4. Step 4: Simplify right side
    1,381.70x = 1,330,814.82
  5. Step 5: Solve for x
    x = 1,330,814.82/1,381.70
  6. Step 6: Final answer
    x = 963.18

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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.