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Finding the Fourth Proportional to 990.94, 1,487.74 and 638.58

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Solution

The fourth proportional to 990.94, 1,487.74 and 638.58 is: 958.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.94 : 1,487.74 = 638.58 : x
  2. Step 2: Convert to fraction form
    990.94/1,487.74 = 638.58/x
  3. Step 3: Cross multiply
    990.94x = 1,487.74 × 638.58
  4. Step 4: Simplify right side
    990.94x = 950,041.01
  5. Step 5: Solve for x
    x = 950,041.01/990.94
  6. Step 6: Final answer
    x = 958.73

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.