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Finding the Fourth Proportional to 1,371.08, 1,891.64 and 781.40

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Solution

The fourth proportional to 1,371.08, 1,891.64 and 781.40 is: 1,078.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,371.08 : 1,891.64 = 781.40 : x
  2. Step 2: Convert to fraction form
    1,371.08/1,891.64 = 781.40/x
  3. Step 3: Cross multiply
    1,371.08x = 1,891.64 × 781.40
  4. Step 4: Simplify right side
    1,371.08x = 1,478,127.50
  5. Step 5: Solve for x
    x = 1,478,127.50/1,371.08
  6. Step 6: Final answer
    x = 1,078.08

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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.