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Finding the Fourth Proportional to 1,379.70, 2,069.60 and 405.86

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Solution

The fourth proportional to 1,379.70, 2,069.60 and 405.86 is: 608.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,379.70 : 2,069.60 = 405.86 : x
  2. Step 2: Convert to fraction form
    1,379.70/2,069.60 = 405.86/x
  3. Step 3: Cross multiply
    1,379.70x = 2,069.60 × 405.86
  4. Step 4: Simplify right side
    1,379.70x = 839,955.48
  5. Step 5: Solve for x
    x = 839,955.48/1,379.70
  6. Step 6: Final answer
    x = 608.80

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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.