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Finding the Fourth Proportional to 1,378.78, 1,902.09 and 818.93

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Solution

The fourth proportional to 1,378.78, 1,902.09 and 818.93 is: 1,129.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.78 : 1,902.09 = 818.93 : x
  2. Step 2: Convert to fraction form
    1,378.78/1,902.09 = 818.93/x
  3. Step 3: Cross multiply
    1,378.78x = 1,902.09 × 818.93
  4. Step 4: Simplify right side
    1,378.78x = 1,557,679.22
  5. Step 5: Solve for x
    x = 1,557,679.22/1,378.78
  6. Step 6: Final answer
    x = 1,129.75

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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.