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Finding the Fourth Proportional to 1,311.27, 1,809.51 and 780.15

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Solution

The fourth proportional to 1,311.27, 1,809.51 and 780.15 is: 1,076.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.27 : 1,809.51 = 780.15 : x
  2. Step 2: Convert to fraction form
    1,311.27/1,809.51 = 780.15/x
  3. Step 3: Cross multiply
    1,311.27x = 1,809.51 × 780.15
  4. Step 4: Simplify right side
    1,311.27x = 1,411,689.23
  5. Step 5: Solve for x
    x = 1,411,689.23/1,311.27
  6. Step 6: Final answer
    x = 1,076.58

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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.