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Finding the Fourth Proportional to 777.71, 1,171.89 and 643.76

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Solution

The fourth proportional to 777.71, 1,171.89 and 643.76 is: 970.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    777.71 : 1,171.89 = 643.76 : x
  2. Step 2: Convert to fraction form
    777.71/1,171.89 = 643.76/x
  3. Step 3: Cross multiply
    777.71x = 1,171.89 × 643.76
  4. Step 4: Simplify right side
    777.71x = 754,410.05
  5. Step 5: Solve for x
    x = 754,410.05/777.71
  6. Step 6: Final answer
    x = 970.05

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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.