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Finding the Fourth Proportional to 1,369.73, 1,890.17 and 780.21

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Solution

The fourth proportional to 1,369.73, 1,890.17 and 780.21 is: 1,076.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,369.73 : 1,890.17 = 780.21 : x
  2. Step 2: Convert to fraction form
    1,369.73/1,890.17 = 780.21/x
  3. Step 3: Cross multiply
    1,369.73x = 1,890.17 × 780.21
  4. Step 4: Simplify right side
    1,369.73x = 1,474,725.63
  5. Step 5: Solve for x
    x = 1,474,725.63/1,369.73
  6. Step 6: Final answer
    x = 1,076.66

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1.5x scale

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.