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Finding the Fourth Proportional to 1,379.68, 2,069.82 and 405.70

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Solution

The fourth proportional to 1,379.68, 2,069.82 and 405.70 is: 608.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,379.68 : 2,069.82 = 405.70 : x
  2. Step 2: Convert to fraction form
    1,379.68/2,069.82 = 405.70/x
  3. Step 3: Cross multiply
    1,379.68x = 2,069.82 × 405.70
  4. Step 4: Simplify right side
    1,379.68x = 839,725.97
  5. Step 5: Solve for x
    x = 839,725.97/1,379.68
  6. Step 6: Final answer
    x = 608.64

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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.