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Finding the Fourth Proportional to 1,315.71, 1,815.21 and 791.64

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Solution

The fourth proportional to 1,315.71, 1,815.21 and 791.64 is: 1,092.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,315.71 : 1,815.21 = 791.64 : x
  2. Step 2: Convert to fraction form
    1,315.71/1,815.21 = 791.64/x
  3. Step 3: Cross multiply
    1,315.71x = 1,815.21 × 791.64
  4. Step 4: Simplify right side
    1,315.71x = 1,436,992.84
  5. Step 5: Solve for x
    x = 1,436,992.84/1,315.71
  6. Step 6: Final answer
    x = 1,092.18

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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.