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Finding the Fourth Proportional to 990.05, 1,366.25 and 640.74

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Solution

The fourth proportional to 990.05, 1,366.25 and 640.74 is: 884.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.05 : 1,366.25 = 640.74 : x
  2. Step 2: Convert to fraction form
    990.05/1,366.25 = 640.74/x
  3. Step 3: Cross multiply
    990.05x = 1,366.25 × 640.74
  4. Step 4: Simplify right side
    990.05x = 875,407.82
  5. Step 5: Solve for x
    x = 875,407.82/990.05
  6. Step 6: Final answer
    x = 884.21

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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.