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Finding the Fourth Proportional to 781.44, 1,172.14 and 643.93

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Solution

The fourth proportional to 781.44, 1,172.14 and 643.93 is: 965.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.44 : 1,172.14 = 643.93 : x
  2. Step 2: Convert to fraction form
    781.44/1,172.14 = 643.93/x
  3. Step 3: Cross multiply
    781.44x = 1,172.14 × 643.93
  4. Step 4: Simplify right side
    781.44x = 754,776.11
  5. Step 5: Solve for x
    x = 754,776.11/781.44
  6. Step 6: Final answer
    x = 965.88

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.