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Finding the Fourth Proportional to 990.42, 1,367.22 and 641.28

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Solution

The fourth proportional to 990.42, 1,367.22 and 641.28 is: 885.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.42 : 1,367.22 = 641.28 : x
  2. Step 2: Convert to fraction form
    990.42/1,367.22 = 641.28/x
  3. Step 3: Cross multiply
    990.42x = 1,367.22 × 641.28
  4. Step 4: Simplify right side
    990.42x = 876,770.84
  5. Step 5: Solve for x
    x = 876,770.84/990.42
  6. Step 6: Final answer
    x = 885.25

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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.