Home / 1,369.92-1,890.21-780.30

Finding the Fourth Proportional to 1,369.92, 1,890.21 and 780.30

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Solution

The fourth proportional to 1,369.92, 1,890.21 and 780.30 is: 1,076.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,369.92 : 1,890.21 = 780.30 : x
  2. Step 2: Convert to fraction form
    1,369.92/1,890.21 = 780.30/x
  3. Step 3: Cross multiply
    1,369.92x = 1,890.21 × 780.30
  4. Step 4: Simplify right side
    1,369.92x = 1,474,930.86
  5. Step 5: Solve for x
    x = 1,474,930.86/1,369.92
  6. Step 6: Final answer
    x = 1,076.65

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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.