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Finding the Fourth Proportional to 811.32, 1,211.96 and 688.30

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Solution

The fourth proportional to 811.32, 1,211.96 and 688.30 is: 1,028.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.32 : 1,211.96 = 688.30 : x
  2. Step 2: Convert to fraction form
    811.32/1,211.96 = 688.30/x
  3. Step 3: Cross multiply
    811.32x = 1,211.96 × 688.30
  4. Step 4: Simplify right side
    811.32x = 834,190.76
  5. Step 5: Solve for x
    x = 834,190.76/811.32
  6. Step 6: Final answer
    x = 1,028.19

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.