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Finding the Fourth Proportional to 1,370.87, 1,891.95 and 781.55

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Solution

The fourth proportional to 1,370.87, 1,891.95 and 781.55 is: 1,078.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,370.87 : 1,891.95 = 781.55 : x
  2. Step 2: Convert to fraction form
    1,370.87/1,891.95 = 781.55/x
  3. Step 3: Cross multiply
    1,370.87x = 1,891.95 × 781.55
  4. Step 4: Simplify right side
    1,370.87x = 1,478,653.52
  5. Step 5: Solve for x
    x = 1,478,653.52/1,370.87
  6. Step 6: Final answer
    x = 1,078.62

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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.