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Finding the Fourth Proportional to 777.75, 1,171.98 and 643.80

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Solution

The fourth proportional to 777.75, 1,171.98 and 643.80 is: 970.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    777.75 : 1,171.98 = 643.80 : x
  2. Step 2: Convert to fraction form
    777.75/1,171.98 = 643.80/x
  3. Step 3: Cross multiply
    777.75x = 1,171.98 × 643.80
  4. Step 4: Simplify right side
    777.75x = 754,520.72
  5. Step 5: Solve for x
    x = 754,520.72/777.75
  6. Step 6: Final answer
    x = 970.13

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.