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Finding the Fourth Proportional to 780.93, 1,171.40 and 643.42

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Solution

The fourth proportional to 780.93, 1,171.40 and 643.42 is: 965.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.93 : 1,171.40 = 643.42 : x
  2. Step 2: Convert to fraction form
    780.93/1,171.40 = 643.42/x
  3. Step 3: Cross multiply
    780.93x = 1,171.40 × 643.42
  4. Step 4: Simplify right side
    780.93x = 753,702.19
  5. Step 5: Solve for x
    x = 753,702.19/780.93
  6. Step 6: Final answer
    x = 965.13

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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.