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Finding the Fourth Proportional to 781.36, 1,071.90 and 768.40

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Solution

The fourth proportional to 781.36, 1,071.90 and 768.40 is: 1,054.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.36 : 1,071.90 = 768.40 : x
  2. Step 2: Convert to fraction form
    781.36/1,071.90 = 768.40/x
  3. Step 3: Cross multiply
    781.36x = 1,071.90 × 768.40
  4. Step 4: Simplify right side
    781.36x = 823,647.96
  5. Step 5: Solve for x
    x = 823,647.96/781.36
  6. Step 6: Final answer
    x = 1,054.12

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.