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Finding the Fourth Proportional to 813.60, 1,121.64 and 688.98

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Solution

The fourth proportional to 813.60, 1,121.64 and 688.98 is: 949.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.60 : 1,121.64 = 688.98 : x
  2. Step 2: Convert to fraction form
    813.60/1,121.64 = 688.98/x
  3. Step 3: Cross multiply
    813.60x = 1,121.64 × 688.98
  4. Step 4: Simplify right side
    813.60x = 772,787.53
  5. Step 5: Solve for x
    x = 772,787.53/813.60
  6. Step 6: Final answer
    x = 949.84

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.